236 minutes 234 marks - ASTON ACADEMY GCSE PHYSICS

EnergyHigh Demand Questions

Name: ________________________

Class: ________________________

Date: ________________________

Time: 236 minutes

Marks: 234 marks

Comments:

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Figure 1 shows a cyclist riding along a straight, level road at a constant speed.

Figure 1

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(a) Complete the sentences.

As the cyclist rides along the road, the _______________________ energy store

in the cyclist’s body decreases.

The speed of the cyclist is constant when the work done by the cyclist is

_______________________ the work done against air resistance.

(2)

Figure 2 shows how the speed changes as the power output of the cyclist changes.

Figure 2

(b) Write down the equation that links power, time and work done.

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(1)

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(c) Calculate the work done by the cyclist when his power output is 200 W for 1800 seconds.

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Work done = ______________________ J

(3)

(d) Calculate the percentage increase in speed of the cyclist when the power output changesfrom 200 W to 300 W.

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Percentage increase in speed = ___________

(2)

(e) The maximum speed this cyclist can travel on a level road is 14 m/s.

How does cycling uphill affect the maximum speed of this cyclist?

Explain your answer.

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(3)

(Total 11 marks)

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About half of the UK’s electricity is generated in coal-burning power stations and nuclear powerstations.

(a) Coal-burning power stations and nuclear power stations provide a reliable way ofgenerating electricity.

What is meant by a reliable way of generating electricity?

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(b) Over the next few years, most of the older nuclear power stations in the UK will be closeddown, and the process of decommissioning will start.

What does it mean to decommission a nuclear power station?

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(1)

(c) Climate change has been strongly linked to the emission of carbon dioxide. Manygovernments around the world are committed to reducing carbon dioxide emissions.

Generating electricity can increase carbon dioxide emissions.

The companies generating electricity could reduce carbon dioxide emissions.

Give two ways the companies could do this.

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2. _________________________________________________________________

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(2)

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(d) Electricity is distributed from power stations to consumers along the National Grid.

The voltage across the overhead cables of the National Grid needs to be much higher thanthe output voltage from the power station generators.

Explain why.

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(Total 7 marks)

The diagram below shows four stages in the production of electricity by a coal-fired powerstation.

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(a) (i) Write down two environmental problems which are caused by burning coal togenerate electricity.

1. ____________________________________________________________

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2. ____________________________________________________________

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(ii) How may these environmental problems be reduced?

1. ____________________________________________________________

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2. ____________________________________________________________

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(4)

(b) Some data for Didcot coal-fired power station is given below.

Number of generators 4Maximum continuous power rating of a generator 500 MW at 23 500 VEnergy content of coal used 2.66 × 1010 J per tonneTotal quantity of coal used each day 18 289 tonnes

Use the given data to calculate:

(i) the total electrical energy output each day.

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Answer ________________________J/day

(ii) the total input of coal energy each day.

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Answer ________________________J/day

(iii) the efficiency of the power station.

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Answer ________________________ %

(8)

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(c) Energy is conserved.

(i) Choose one of the stages in the diagram at the start of the question.State what happens to the wasted energy during this stage.

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(ii) Explain what happens to all wasted energy during energy transfers.

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(3)

(Total 15 marks)

Antarctica is a huge land mass surrounding the Earth’s south pole. It is covered in a very thicklayer of ice and is the only remaining large area of the Earth’s surface that has not been affectedvery much by humans.

There are, however, teams of scientists from various countries studying Antarctica. Thesescientists need electricity for lighting, for their computers and other scientific instruments and tocommunicate, via satellite, with the rest of the world. The temperature in Antarctica is alwayssub-zero, so the scientists need some way of keeping their buildings warm. They also need fuelto be able to get around on their snowmobiles.

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Scientists cannot avoid affecting the environment. However, they want to affect it as littleas possible.

Atmospheric pollution produced in one country eventually affects the whole of the Earth’satmosphere. The hole that appears each year in the ozone layer above Antarctica, for example,is mainly caused by pollutants such as CFCs from countries in the northern half of the Earth.

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Discuss the advantages and disadvantages of using the following energy sources to meet thescientists’ needs:

• solar energy

• energy from the wind

• natural gas (present in large quantities deep down in the Antarctic land mass)

• diesel oil (which would have to be imported)

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(Total 10 marks)

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The image below shows a solar thermal power station that has been built in a hot desert.

The power station uses energy from the Sun to heat water to generate electricity.

Energy from the Sun is reflected towards a solar receiver using many mirrors.

© Kim Steele/Photodisc/Thinkstock

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(a) (i) Which part of the electromagnetic spectrum provides most of the energy to heat thewater in a solar thermal power station?

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(ii) Describe how heated water is used to generate electricity by thissolar thermal power station.The process is the same as in a fossil fuel power station.

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(b) A new type of solar power station, called a solar storage power station, is able to storeenergy from the Sun by heating molten chemical salts.The stored energy can be used to generate electricity at night.

(i) It is important that the molten chemical salts have a high specific heat capacity.Suggest one reason why.

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(1)

(ii) The solar storage power station can store a maximum of 2 200 000 kWh of energy.The solar storage power station can supply a town with a maximum electrical powerof 140 000 kW.

Calculate for how many hours the energy stored by the solar storage power stationcan supply the town with electrical power.

Give your answer to 2 significant figures.

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Time = __________________ hours

(3)

(iii) Table 1 gives information about the place where the solar storage power station hasbeen built.

Table 1

SeasonMean number ofdaylight hours

Mean power received fromthe Sun per

square metre in kW

Spring 11.5 0.90

Summer 13.5 1.10

Autumn 12.0 0.95

Winter 10.5 0.71

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The solar storage power station does not operate at the maximum possible electricaloutput every day of the year.

Suggest why.

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(2)

(c) Power stations do not work at maximum possible electrical output all the time.The ‘capacityfactor’ of a power station is calculated using the equation:

Table 2 shows capacity factors for different types of power station.

Table 2

Type of power stationRenewable energy

sourceCapacity factor

Coal No 0.41

Natural gas No 0.48

Nuclear No 0.66

Solar thermal Yes 0.33

Tidal Yes 0.26

Wind turbine Yes 0.30

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(i) Compare the capacity factors of the renewable power stations with those of thenon-renewable power stations in Table 2.Explain the reason for the difference between the capacity factors.

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(3)

(ii) The capacity factor of a solar storage power station is higher than for all otherrenewable power stations.Suggest one reason why.

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(1)

(Total 14 marks)

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The map below shows an industrial region (shaded).

The prevailing wind is from the west. There is a nearby mountainous area, from which a riverflows through the region. The major road and rail links are shown.

A power station is to be built to supply electrical energy to the region. The energy will be for arange of domestic and industrial uses.

The choice is between a coal fired power station, wind turbines and a hydroelectric scheme.

Three local groups each support a different option. Choose which option you would support andjustify your choice by making reference to the financial, social and environmental implications ofyour choice compared with those of the alternative systems.

(Total 8 marks)

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(a) Most electricity in Britain is generated by coal fired power stations.

Complete the sequence of useful energy transfers which take place in the power station.

(1)

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(b) The diagram shows a wind turbine which is used to produce electricity using energy fromthe wind.

(i) What is the source of energy which creates winds?

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(ii) Explain the advantage of using a wind turbine to produce electricity.

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(Total 4 marks)

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The outline diagram below shows a tidal power generating system.

Gates in the barrage are open when the tide is coming in and the basin is filling to the high tidelevel. The gates are then closed as the tide begins to fall.

Once the tide outside the barrage has dropped the water can flow through large turbines in thebarrage which drive generators to produce electrical energy.

In one second 1.2 × 109 kg of water flows through the turbines at a speed of 20 m/s.

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(a) When used with a water speed of 20 m/s the system has an efficiency of 90% in convertingthe kinetic energy of the water into electrical energy. Calculate the power output of thegenerators.

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(b) The power output of a coal fired power station is 1000 MW (1 x 109 W).

(i) Suggest two advantages of coal fired power stations over tidal powergenerating systems.

1. ____________________________________________________________

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2. ____________________________________________________________

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(ii) Suggest two advantages of tidal power generating systems over coal firedpower stations.

1. ____________________________________________________________

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2. ____________________________________________________________

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(iii) Suggest and explain one disadvantage of a tidal power generating system.

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(Total 8 marks)

The pie charts show the relative proportions of electricity generated in Japan from differentenergy sources in 1975 and 2005.

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(a) Describe the main differences in the energy sources used in 2005 compared with 1975.

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(b) In the UK, nuclear fuels are used to generate about 21% of the total electricity supply.

(i) What is the name of the process by which a nuclear fuel produces heat?

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(ii) Explain how the heat released from a nuclear fuel is used to generate electricity inpower stations.

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(iii) Some people have suggested that more nuclear power stations should be built in theUK.

Give two reasons to support this suggestion.

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(2)

(iv) Nuclear power stations create dangerous waste.

Why is the waste from a nuclear power station dangerous?

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(c) A headline from a newspaper article is shown below.

Explain the possible link between climate change and coal-burning power stations.

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(Total 9 marks)

(a) The table gives information about some ways of reducing the energy consumption in ahouse.

Method of reducing energyconsumption

Installationcost in £

Annual saving onenergy bills in £

Fit a new hot water boiler 1800 200

Fit a solar water heater 2400 100

Fit under floor heating 600 50

Fit thermostatic radiator valves 75 20

Which way of reducing energy consumption is most cost effective over a 10-year period?

To obtain full marks you must support your answer with calculations.

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(b) Explain why using an energy-efficient light bulb instead of an ordinary light bulb reducesthe amount of carbon dioxide emitted into the atmosphere.

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(2)

(Total 5 marks)

The diagram shows a wind turbine.

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(a) The blades of the turbine are 20 metres long. On average, 15 000 kg of air, moving at aspeed of 12 m/s, hit the blades every second.

Calculate the kinetic energy of the air hitting the blades every second.

Show clearly how you work out your answer.

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Kinetic energy = _________________________ J

(2)

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(b) Part of the kinetic energy of the wind is transformed into electrical energy.The diagram shows that, for the same wind speed, the power output of a turbine, inkilowatts, depends on the length of the turbine blades.

Give a reason why doubling the diameter of the blades more than doubles the poweroutput of a turbine.

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(Total 3 marks)

(a) Explain how energy is produced in the Sun.

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(b) Read the following article that appeared in a magazine.

“Conservation of energy is important in today’s society. Energy sources, such as oil andcoal, which have been used for the development of an industrial society, cannot be reliedupon as heavily in the future. Renewable energy sources cannot provide such largequantities of energy for society without causing problems.”

(i) Give two reasons why oil should not be relied on as a major source of energy for thefuture.

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(ii) Energy from the wind is a renewable energy resource. State three problems whichmay arise if the wind were to be used to meet the energy requirements of a largeindustrial city in Britain.

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2. ____________________________________________________________

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(Total 8 marks)

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There is an increasing demand for electricity and the reserve of fossil fuels is decreasing. A wayto meet increasing demand for electricity is to build new nuclear power stations. Some peoplefeel that no new nuclear power stations should be built because of the risks associated withnuclear fuels.

(a) Outline the arguments that a scientist working in the nuclear power industry could use tojustify the building of more nuclear power stations in the future.

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(b) Nuclear waste is a problem that must be dealt with. One possible solution would be to burythe waste deep underground.

Suggest one reason why some people are against burying nuclear waste.

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(1)

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(c) Electricity can also be generated using renewable energy sources.

Look at this information from a newspaper report.

• The energy from burning bio-fuels, such aswoodchip and straw, can be usedto generate electricity.

• Plants for bio-fuels use up carbon dioxideas they grow.

• Farmers get grants to grow plants forbio-fuels.

• Electricity generated from bio-fuels can besold at a higher price than electricitygenerated from burning fossilfuels.

• Growing plants for bio-fuels offers newopportunities for rural communities.

Suggest why, apart from the declining reserves of fossil fuels, power companies should usemore bio-fuels and less fossil fuels to generate electricity.

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(Total 7 marks)

Over the next 15 years, some of the older nuclear power stations will be closed down, and theprocess of decommissioning will start. In the same period, several countries plan to build anumber of new nuclear power stations.

(a) (i) What does it mean to decommission a nuclear power station?

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(ii) How does decommissioning affect the overall cost of electricity generated usingnuclear fuels?

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(1)

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(b) Uranium is a fuel used in nuclear power stations to generate electricity.

Graph 1 compares how the electricity generated from one kilogram of nuclear fuel changedbetween 1980 and 2005 in three different types of nuclear power station.

(i) Compare the efficiency of the three types of power station, K, L and M, between 1980and 2005.

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(2)

Graph 2 shows two different predictions for the global growth in uranium demand over thenext few years.

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(ii) Suggest reasons why it is not possible to predict accurately how much uranium willbe needed in 2025.

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(2)

(Total 6 marks)

(a) Nuclear fuels and the wind are two of the energy sources used to generate electricity in theUK.

Explain the advantages of using energy from nuclear fuels to generate electricity ratherthan using energy from the wind.

Include in your answer a brief description of the process used to generate electricity fromnuclear fuels.

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(4)

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(b) In the UK, most electricity is generated in power stations that emit carbon dioxide into theatmosphere. The impact of these power stations on the environment could be reduced bythe increased use of 'carbon capture' technology.

Describe how 'carbon capture' would prevent the build-up of carbon dioxide in theatmosphere.

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(2)

(Total 6 marks)

The miners working in a salt mine use smooth wooden slides to move quickly from one level toanother.

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(a) A miner of mass 90 kg travels down the slide.

Calculate the change in gravitational potential energy of the miner when he moves 15 mvertically downwards.

gravitational field strength = 10 N/kg


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Change in gravitational potential energy = _________________________ J

(2)

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(b) Calculate the maximum possible speed that the miner could reach at the bottom of theslide.


Give your answer to an appropriate number of significant figures.

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Maximum possible speed = _________________________ m/s

(3)

(c) The speed of the miner at the bottom of the slide is much less than the calculatedmaximum possible speed.

Explain why.

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(3)

(Total 8 marks)

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The world’s biggest offshore wind farm, built off the Kent coast, started generating electricity inSeptember 2010.

(a) The graph shows how wind speed affects the power output from one of the wind turbines.

In one 4-hour period, the wind turbine transfers 5600 kilowatt-hours of electrical energy.

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Use the data in the graph to calculate the average wind speed during this 4-hour period.


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Average wind speed = ____________________ m/s

(3)

(b) The wind turbines are linked to the National Grid by underwater cables.

(i) What is the National Grid?

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(1)

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(ii) How is the National Grid designed to reduce energy losses during transmission?

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(1)

(c) Read this extract from a newspaper.

Explain one way in which the islanders could try to ensure that a similar power crisis doesnot happen in the future.

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(Total 7 marks)

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(a) Figure 1 shows the forces acting on a model air-powered rocket just after it has beenlaunched vertically upwards.

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(i) How does the velocity of the rocket change as the rocket moves upwards?

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Give a reason for your answer.

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(2)

(ii) The velocity of the rocket is not the same as the speed of the rocket.

What is the difference between the velocity of an object and the speed of an object?

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(b) The speed of the rocket just after being launched is 12 m / s.The mass of the rocket is 0.05 kg.

(i) Calculate the kinetic energy of the rocket just after being launched.

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Kinetic energy = _____________________ J

(2)

(ii) As the rocket moves upwards, it gains gravitational potential energy.

State the maximum gravitational potential energy gained by the rocket.

Ignore the effect of air resistance.

Maximum gravitational potential energy = _____________________ J

(1)

(iii) Calculate the maximum height the rocket will reach.

Ignore the effect of air resistance.

Gravitational field strength = 10 N/kg.

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Maximum height = _____________________ m

(2)

(iv) Figure 2 shows four velocity−time graphs.

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Taking air resistance into account, which graph, A, B, C or D, shows how the velocityof the rocket changes as it falls from the maximum height it reached until it just hitsthe ground?

Write the correct answer in the box.

(1)

(c) The rocket can be launched at different angles to the horizontal.The horizontal distance the rocket travels is called the range.

Figure 3 shows the paths taken by the rocket when launched at different angles.Air resistance has been ignored.

What pattern links the angle at which the rocket is launched and the range of the rocket?

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(Total 11 marks)

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(a) In the UK, over 70% of the electricity is generated in power stations that burn fossil fuels.

(i) Explain one effect that burning fossil fuels has on the environment.

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(ii) Give one way the effect on the environment described in part (a)(i) could be reduced.

Assume the amount of fossil fuels burnt stays the same.

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(1)

(b) Electricity can also be generated in a pumped storage hydroelectric power station.

An advantage of pumped storage hydroelectric power stations is the short start-up timethey have.

(i) What is the importance of the short start-up time?

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(ii) Give one other advantage of a pumped storage hydroelectric power station.

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(c) Read the extract below from a newspaper article.

(i) In the UK, the proportion of electricity generated using wind turbines is due toincrease a lot. Some opponents of wind turbines think this increase will cause bigfluctuations in the electricity supply.

Suggest one reason why this may be true.

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(ii) Between 2002 and 2008 the amount of electricity used for lighting in homes in the UKdecreased.

Suggest one reason why.

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(Total 7 marks)

An electric immersion heater is used to heat the water in a domestic hot water tank.When the immersion heater is switched on the water at the bottom of the tank gets hot.

(a) Complete the following sentence.

The main way the energy is transferred through the copper wall of the water tank is

by the process of ________________________________________ .

(1)

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(b) The immersion heater has a thermostat to control the water temperature.

When the temperature of the water inside the tank reaches 58°C the thermostat switchesthe heater off. The thermostat switches the heater back on when the temperature of thewater falls to 50°C.

Graph A shows how the temperature of the water inside a hot water tank changes withtime. The tank is not insulated.

Time in hours

(i) The temperature of the water falls at the fastest rate just after the heater switches off.

Explain why.

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(2)

(ii) To heat the water in the tank from 50°C to 58°C the immersion heater transfers4032 kJ of energy to the water.

Calculate the mass of water in the tank.

Specific heat capacity of water = 4200 J/kg°C

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Mass = _______________________________ kg

(3)

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(iii) An insulating jacket is fitted to the hot water tank.

Graph B shows how the temperature of the water inside the insulated hot water tankchanges with time.

Time in hours

An insulating jacket only costs £12.

By comparing Graph A with Graph B, explain why fitting an insulating jacket to a hotwater tank saves money.

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(3)

(Total 9 marks)

A ‘can-chiller’ is used to make a can of drink colder.

The image below shows a can-chiller.

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(a) The initial temperature of the liquid in the can was 25.0 °C.The can-chiller decreased the temperature of the liquid to 20.0 °C.The amount of energy transferred from the liquid was 6930 J.The mass of liquid in the can was 0.330 kg.

Calculate the specific heat capacity of the liquid.

Give the unit.

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Specific heat capacity = _____________________ unit ________________

(4)

(b) Energy is transferred through the metal walls of the can of drink by conduction.Explain how.

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(4)

(c) The energy from the can of drink is transferred to the air around the can-chiller.A convection current is set up around the can-chiller. Explain how.

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(3)

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(d) The can-chiller has metal cooling fins that are designed to transfer energy quickly to thesurroundings.

Give two features that would help the metal cooling fins to transfer energy quickly to thesurroundings.

1. _________________________________________________________________

2. _________________________________________________________________

(2)

(Total 13 marks)

Nuclear power stations generate electricity through nuclear fission. Electricity can also begenerated by burning shale gas.

(a) Shale gas is natural gas trapped in rocks. Shale gas can be extracted by a process calledfracking. There is some evidence that fracking causes minor earthquakes. Burning shalegas adds carbon dioxide to the atmosphere.

Describe the advantages of nuclear power compared with the use of shale gas to generateelectricity.

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(3)

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(b) What is the name of one fuel used in nuclear power stations?

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(c) Describe the process of nuclear fission.

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(4)

(Total 8 marks)

The diagram below shows a wind turbine.23

(a) At a particular wind speed, a volume of 2.3 × 104 m3 of air passes the blades each second.

The density of air is 1.2 kg/m3.

Calculate the mass of air passing the blades per second.

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Mass of air per second = ____________________ kg

(3)

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(b) The power output of the turbine is directly proportional to the kinetic energy of the airpassing the blades each second.

Describe the effect on the power output when the wind speed is halved.

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(3)

(c) At a different wind speed, the wind turbine has a power output of 388 kW.

The mass of air passing the wind turbine each second is 13 800 kg.

Calculate the speed of the air passing the blades each second.

Assume that the process is 100% efficient.

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Speed of air = ____________________ m/s

(3)

(Total 9 marks)

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The figure below shows a student before and after a bungee jump.

The bungee cord has an unstretched length of 20.0 m.

The mass of the student is 50.0 kg.

The gravitational field strength is 9.8 N / kg.

(a) Write down the equation which links gravitational field strength, gravitational potentialenergy, height and mass.

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(1)

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(b) Calculate the change in gravitational potential energy from the position where the studentjumps to the point 20.0 m below.

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___________________________________________________________________

___________________________________________________________________

Change in gravitational potential energy = _____________ J

(2)

of 84Aston Academy

(c) 80% of this change in gravitational potential energy has been transferred to the student’skinetic energy store.

How much has the student’s kinetic energy store increased after falling 20.0 m?

Kinetic energy gained = ________________________ J

(1)

(d) Calculate the speed of the student after falling 20.0 m.

Give your answer to two significant figures.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

Speed = __________________________ m / s

(4)

(e) At the lowest point in the jump, the energy stored by the stretched bungee cord is 24.5 kJ.

The bungee cord behaves like a spring.

Calculate the spring constant of the bungee cord.

Use the correct equation from the Physics Equation Sheet.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

Spring constant = ________________________ N / m

(3)

(Total 11 marks)

of 84Aston Academy

All European Union countries are expected to generate 20% of their electricity using renewableenergy sources by 2020.

The estimated cost of generating electricity in the year 2020 using different energy sources isshown in Table 1.

Table 1

Energy source Estimated cost (in the year 2020)in pence per kWh

Nuclear 7.8

Solar 25.3

Tidal 18.8

Wind 10.0

25

France generated 542 billion kWh of electricity using nuclear power stations in 2011.France used 478 billion kWh of electricity and sold the rest of the electricity to other countries in2011.

(a) France may continue generating large amounts of electricity using nuclear power stationsinstead of using renewable energy resources.

Suggest two reasons why.

1. _________________________________________________________________

___________________________________________________________________

2. _________________________________________________________________

___________________________________________________________________

(2)

(b) Give two disadvantages of generating electricity using nuclear power stations.

1. _________________________________________________________________

___________________________________________________________________

2. _________________________________________________________________

___________________________________________________________________

(2)

of 84Aston Academy

(c) A panel of solar cells has an efficiency of 0.15.

The total power input to the panel of solar cells is 3.2 kW.

Calculate the useful power output of this panel of solar cells in kW.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

Useful power output = _______________ kW

(2)

(d) Table 2 shows the manufacturing cost and efficiency of different types of panels of solarcells.

Table 2

Type of Solar Panel Cost to manufacture a 1 m2

solar panel in £Efficiency in %

A 40.00 20

B 22.50 15

C 5.00 10

Some scientists think that having a low manufacturing cost is more important thanimproving the efficiency of solar cells.

Use information from Table 2 to suggest why.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

(2)

(Total 8 marks)

of 84Aston Academy

Figure 1 shows an exercise device called a chest expander. The three springs are identical.

Figure 1

A person pulls outwards on the handles and does work to stretch the springs.

(a) Complete the following sentence.

When the springs are stretched ___________ ___________ energy is stored in thesprings.

(1)

26

(b) Figure 2 shows how the extension of a single spring from the chest expander depends onthe force acting on the spring.

Figure 2

(i) How can you tell, from Figure 2, that the limit of proportionality of the spring has notbeen exceeded?

______________________________________________________________

______________________________________________________________

(1)

of 84Aston Academy

(ii) Use data from Figure 2 to calculate the spring constant of the spring.Give the unit.

______________________________________________________________

______________________________________________________________

______________________________________________________________

Spring constant = ___________ Unit ___________

(3)

(iii) Three identical resistors joined in parallel in an electrical circuit share the total currentin the circuit.

In a similar way, the three springs in the chest expander share the total force exerted.

By considering this similarity, use Figure 2 to determine the total force exerted on thechest expander when each spring is stretched by 0.25 m.

______________________________________________________________

______________________________________________________________

Total force = ___________ N

(2)

(c) The student in Figure 3 is doing an exercise called a chin-up.

Figure 3

of 84Aston Academy

Each time the student does one chin-up he lifts his body 0.40 m vertically upwards.The mass of the student is 65 kg.The student is able to do 12 chin-ups in 60 seconds.

Calculate the power developed by the student.

Gravitational field strength = 10 N/kg

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

Power = ___________ W

(3)

(Total 10 marks)

Under the same conditions, different materials heat up and cool down at different rates.

(a) What is meant by specific heat capacity?

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

(2)

27

of 84Aston Academy

(b) ‘Quenching’ is a process used to change the properties of steel by cooling it rapidly.

The steel is heated to a very high temperature and then placed in a container of cold water.

(i) A metalworker quenches a steel rod by heating it to a temperature of 900 °C beforeplacing it in cold water. The mass of the steel rod is 20 kg.

The final temperature of the rod and water is 50 °C.

Calculate the energy transferred from the steel rod to the water.

Specific heat capacity of steel = 420 J/kg °C.

______________________________________________________________

______________________________________________________________

______________________________________________________________

Energy transferred = ____________________ J

(3)

(ii) The temperature of the steel rod eventually returns to room temperature.

Compare the movement and energies of the particles in the steel rod and in the air atroom temperature.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

(3)

of 84Aston Academy

(iii) When the steel rod is being quenched, the temperature of the water rises to 50 °C.After a few hours the water cools down to room temperature.

Some of the cooling of the water is due to evaporation.

Explain in terms of particles how evaporation causes the cooling of water.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

(4)

(Total 12 marks)

of 84Aston Academy

Mark schemes

(a) chemical1

equal to

allow the same as1

in this order only

1

(b)

1

(c)

1

W = 200 × 18001

W = 360 000 (J)1

an answer of 360 000 (J) scores 3 marks

(d) 11 − 9.5 = 1.5 (m/s)allow a change in speed between 1.2 and 1.5 (m/s)

1

allow an answer consistent with their change in speed

an answer of 16 (%) scores 2 marks1

an answer that rounds to 15.8 (%) scores 2 marks

(e) maximum speed is lower1

because maximum power output of cyclist is constant

allow maximum force on pedals is constant1

(but) additional work is done (against gravity)

do not accept additional work done against friction or air resistance

orgravitational potential energy (of cyclist) is increased

1

[11]

of 84Aston Academy

(a) any one from:

• energy / source is constant

• energy / source does not rely on uncontrollable factors

accept a specific example, eg the weather

• can generate all of the time

will not run out is insufficient1

2

(b) (dismantle and) remove radioactive waste / materials / fuel

accept nuclear for radioactive

knock down / shut down is insufficient1

(c) any two from:

• reduce use of fossil fuelled power stations

accept specific fossil fuelaccept use less fossil fuel

• use more nuclear power

accept build new nuclear power stations

• use (more) renewable energy sources

accept a named renewable energy sourcedo not accept natural for renewable

• make power stations more efficient

• (use) carbon capture (technology)

do not accept use less non-renewable (energy) sources2

(d) (by increasing the voltage) the current is reduced1

this reduces the energy / power loss (from the cable)

accept reduces amount of waste energyaccept heat for energydo not accept stops energy loss

1

and this increases the efficiency (of transmission)1

[7]

(a) (i) much ash producedacid rainglobal warming/greenhouse effect

any 2 for 1 mark each2

3

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(ii) landscaping/road building*removal of exhaust gases*use alternative source not producingCO2* (*sequential (i))

for 1 mark each2

(b) (i) E = 5 × 108 × 3600 × 24 J/day× 4 (for 4 generators) (sequential on P × t) = 1.73 × 1014 (J/day)

for 1 mark each3

(ii) 2.66 × 1010 × 18 829 = 4.86 × 1014

for 1 mark each2

(iii) Eff = output/inputEff = 1.73/4.86Eff = 0.36 or worked to a percentage

for 1 mark each3

(c) (i) boiler – heat to surroundingsturbine – not all steam energy used/heat/sound lost to surroundingsgenerator – heat in wires/coils/heat to surroundingstransformer – heat in wires/coils/heat tosurroundings

any 1 for 1 mark1

(ii) energy spread out/dilutedas surroundings become warmer/energy lost as heatdifficult to use for further useful energy/transfers

any 2 for 1 mark each2

[15]

ideas that

• direct solar radiation will provide enough energy to heat the (specially designed) buildingsduring the period Oct-Mar / summer

• solar cells will produce plenty of electricity in Oct-Mar / summer (when wind generatorsproduce little)

• a couple of wind generators will produce all electricity needed (for all but heating) Apr-Oct /winter

4

of 84Aston Academy

• number required makes wind generators unsuitable for heating / buildings

• no solar energy in June and July / little in winter

• solar / wind have little effect on environment

• or cause no air pollution

• solar and wind complement each other

• or together provide energy all year

• fuel / gas / diesel can provide energy all the time / at any time

• fuel / gas / diesel needed for transport

• fuel / gas / diesel needed for heating in winter

• diesel has to be imported

• diesel likely to freeze

• gas wouldn’t have to be imported

• drilling for gas difficult / harms environment

• but atmospheric pollution a global rather than local matter so any produced in Antarcticdoesn’t matter much

(deduct 1 mark (to minm. zero) for incorrect claims about destroying ozone layer)

• gas produces less carbon dioxide (for the same energy released) than diesel*

• gas produces less sulphur dioxide (for the same energy released than diesel*

(* these ideas met by candidates in Q.16 so must be allowed, though not required)

any ten for 1 mark each

[10]

(a) (i) infrared (radiation)

accept IR (radiation)1

(ii) (heated) water turns to steam

ignore reference to fossil fuels

do not accept water evaporates to steam1

steam turns a turbine1

turbine turns a generator

accept turbine connected to a generator1

5

of 84Aston Academy

(b) (i) (so the molten salts) can store large amounts of energy

accept there is a small temperature change for a large energytransfer

accept heat for energy1

(ii) 16 (hours)

an answer that rounds to 16 gains 2 marks eg 15.71

allow 1 mark for a correct substitution ie 2 200 000 = 140 000 × t3

(iii) the number of daylight hours varies

less sunlight is insufficient1

the (mean) power (received from the Sun per square metre) varies

accept an answer in terms of maximum possible electrical outputonly possible during Summer for 1 mark

1

(c) (i) non-renewable power stations have higher Capacity Factors than renewablepower stations

1

fuel (for non-renewable power stations) is always available

reference to non-renewable power stations operating all the time isinsufficientnon-renewable energy sources are reliable is insufficient

1

(most) renewable energy sources are unpredictable / unreliable

accept (most) renewable energy sources depend on the weather1

(ii) the (proportion of) time that solar storage power stations can generateelectricity is greater (than for other renewable energy sources)

1

[14]

To gain marks the candidate must

1. Select one option Advantages ) Max 4

2. State 8 valid advantages/disadvantages/relevant Disadvantages) Min 1comparisons with either of the alternatives Comparisons ) If no A or D or C then Max 4 No option then Max 4Look for As, Ds for chosen scheme.Then for Cs compared with A/D for chosen scheme.

6

of 84Aston Academy

Below are listed some of the relevant mark scoring points.

Advantages Disadvantages

Wind Land available to North Initial cost No pollution Many windmills/much land Close/low transmission costs Calm day problem No fuel costs Few long term jobs Renewable energy resource

Coal Waste land to North Pollution Prevailing wind to East Initial costs Good road/rail transport Fuel costs Close/low transmission costs Non-renewable energy Save coal industry Resource Overall labour intensive

Hydroelectric No pollution Possible drought Mountains/lake/river nearby Distant/transmission costs No fuel costs Few jobs created Renewable energy source Possible expensive underground transmission cable Construction of dam affects environment

[8]

(a) internal or thermal or heat or kinetic or movement

electrical

both answers required for one mark1

7

(b) (i) Sun or solar

do not accept sunshine1

(ii) any one of the follow:

• wind turbines produce no (gaseous) pollutants

• wind turbines use renewable energy

• wind turbines produce no (solid) waste

• reduced running costs

do not allow safety1

a supporting statement or comparison or explanation1

[4]

of 84Aston Academy

(a) 90% of 2.10112.16.1011

2

8

(b) (i) Can be located anywhereContinuous outputSustain coal industry

any 2 for 1 mark each

(ii) Low running costNo atmospheric pollutionGives calm coastal waters


(iii) High installation costs – built in seaCoast environmental damage – wildlife disturbanceTime dependence – need dropping tide


(1 for a valid disadvantage, 1 for reason)6

[8]

(a) decrease in oil

PLUS

any one from:

• increase in (proportion of) coal

• increase in (proportion of) nuclear

• increase in (proportion of) gas

must have decrease in (proportion of) oil and increase in (proportionof) coal / nuclear / gas

1

9

(b) (i) (nuclear) fission

accept fision

do not accept any answer that looks like fusion1

(ii) water heated to produce (high pressure) steam1

steam turns turbine which drives generator1

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(iii) any two from:

• produces no pollutant gases

accept named gas or greenhouse gasesaccept no atmospheric pollutionaccept harmful for pollutantaccept does not contribute to global warming

do not accept no pollution on its owndo not accept better for the environment unless qualified

• it is reliable or can generate all of the time

• concentrated energy source or produces a lot of energy from a small mass

• produces only small volume of (solid) waste

• fossil fuels will last longer

accept a named fossil fuelaccept fossil fuels are running out

do not accept fossil fuels are non-renewable unless qualified

• will need to buy less fuel from other countries

accept no new fossil fuel power stations needed

do not accept it is cheapdo not accept import less electricity

2

(iv) it is / can be radioactive

do not accept answers in terms of kills cells / cancer

or emits radiation (from the nuclei)

accept emits gamma (rays)1

(c) coal (burning) power stations / burning coal produces carbon dioxide

they refers to coal-burning power stations

accept sulfur dioxide / nitrogen oxides for CO21

(increased) CO2 increases / contributes to / causes global warming /greenhouse effect

mention of ozone layer negates this mark

do not accept CO2 warms atmosphere1

[9]

of 84Aston Academy

(a) four calculations correctly shown

200 × 10 – 1800 = £200100 × 10 – 2400 = –£140050 × 10 – 600 = –£10020 × 10 – 75 = 125

accept four final answers only or obvious rejection of solar waterheater and underfloor heating, with other two calculationscompleted any 1 complete calculation correctlyshown or showing each saving × 10 of all four calculations = 1 markanswers in terms of savings as a percentage of installation costmay score savings mark only

2

hot water boiler

correct answers only1

10

(b) less electricity / energy to be generated / needed from power stations

accept less demand1

reduction in (fossil) fuels being burnt

accept correctly named fuel

accept answer in terms of:fewer light bulbs required because they last longer (1 mark)less energy used / fuels burnt in production / transport etc. (1 mark)

ignore reference to CO2 or global warming

ignore reference to conservation of energy1

[5]

(a) 1 080 000

allow 1 mark for correct substitution

ie ½ × 15 000 × 12 × 122

11

(b) any one from:

• KE (of wind) more than doubles

• mass of air (hitting blades) more than doubles

• area swept out by blades more than doubles

do not accept blades are larger / have a bigger area

• area swept out by blades increases × 41

[3]

of 84Aston Academy

(a) hydrogen converted to helium1

(nuclear) fusion1

((small) loss in mass) which is converted to large amount of energy1

12

(b) (i) any two from

it is running out/ takes millions of years/finite

not non renewable

allow acid rain do not allow waste

pollution or problem with CO2 production

allow a specific example

more responsible to use fossil fuels for(important) chemical functions

2

(ii) any three from

need lots of land for generators or many generators needed

generators may not be conveniently located

uncertainty of supply

accept the wind may not always blow

social resistance or visual pollution

noise pollution

high initial costs

(possible) interference with (local) radio and TV signals3

[8]

of 84Aston Academy

(a) only accept answers in terms of the argument of the nuclear power scientist any threefrom:

• produces a lot of energy for a small mass of fuel or is a concentrated energy source

accept amount for mass

• it is reliable or it can generate all of the time

• produces no pollutant gases

accept named gas or greenhouse gases do not accept no pollution

• produces only a small volume of (solid) waste

accept amount for volume

• advances in technology will make fuel reserves last much longer

accept an argument in terms of supply and demand3

13

(b) any one from:

• may leak into the ground / environment

• geological changes

accept earthquakes etc

• may get into the food chain

do not accept answers in terms of property prices or ‘damages theenvironment’

• over time if location not correctly recorded it may be excavated1

(c) any three from:

• overall add no carbon dioxide to the environment

accept do not add to global warming

accept they are carbon neutral

• power companies can sell electricity at a higher price

accept power companies make more profit

• opportunity to grow new type crop

accept specific examples e.g. growing plants in swamps

accept extends the life of fossil fuel reserve

• more jobs

• more land cultivated or different types of land utilised3

[7]

of 84Aston Academy

(a) (i) (dismantle and) remove radioactive waste / materials / fuels

accept nuclear for radioactive

do not accept knock down / shut down1

14

(ii) increases it

do not accept it has a negative effect1

(b) (i) if efficiency is not mentioned it must be implied

answers in terms of energy

generated only gains no credit

K most efficientorM least efficient

accept K and / or L are more efficient than M1

(efficiency) of K and L increases, (efficiency) of M (almost) constant /slightly reduced

all 3 power stations must be mentioned to get this mark1

(ii) any two from:

• do not know how many (nuclear) power stations there will be

• power stations may continue to increase in efficiency

• do not know what type of power station new ones will be

accept new methods may be found to generate electricity / energy

accept other ways of generating energy may be expanded

• do not know future energy / electricity demands

accept we may become more energy efficient

• may be new uses for uranium2

[6]

(a) answers must be in terms of nuclear fuels

concentrated source of energy

idea of a small mass of fuel able to generate a lot of electricity1

15

of 84Aston Academy

that is able to generate continuously

accept it is reliable

or can control / increase / decrease electricity generation

idea of available all of the time / not dependent on the weather

ignore reference to pollutant gases1

the energy from (nuclear) fission1

is used to heat water to steam to turn turbine linked to a generator1

(b) carbon dioxide is not released (into the atmosphere)1

but is (caught and) stored (in huge natural containers)1

[6]

(a) 13 500 (J)

allow 1 mark for correct substitution, ie 90 x 10 x 15 provided nosubsequent step shown

2

16

(b) 17or

correctly calculated and answer given to 2 or 3 significant figures

accept 17.3

allow 2 marks for an answer with 4 or more significant figures, ie17.32

or

allow 2 marks for correct substitution, ie 13 500/ their (a) = ½ x 90 xv2

or

allow 1 mark for a statement or figures showing KE = GPE3

(c) work is done1

(against) friction (between the miner and slide)

accept ‘air resistance’ or ‘drag’ for friction1

of 84Aston Academy

(due to the) slide not (being perfectly) smooth

accept miners clothing is rough

or

causing (kinetic) energy to be transferred as heat/internal energy of surroundings

accept lost/transformed for transferred

accept air for internal energy of surroundings1

[8]

(a) 9

allow 2 marks for power = 1400 (kW)

if a subsequent calculation is shown award 1 mark only

or

allow 1 mark for correct substitution and transformation

allow 1 mark for using a clearly incorrect value for power to read acorresponding correct value from the graph

3

17

power =

(b) (i) system of cables and transformers

both required for the mark

ignore reference to pylons

inclusion of power stations / consumers negates the mark

wire(s) is insufficient1

(ii) (uses step-up transformer to) increase pd / voltage

accept (transfers energy / electricity at) high voltageor(uses step-up transformer to) reduce current

accept (transfers energy / electricity at) low current

ignore correct references to step-down transformers1

(c) build a power station that uses a non-renewable fuel or biofuel

accept a named fuel

eg coal or woodorbuy (lots of) petrol / diesel generators

1

of 84Aston Academy

stockpile supplies of the fuel

accept fuel does not rely on the weatherorfuel provides a reliable source of energy

accept as an alternative answer idea of linking with the NationalGrid (1)

and taking power from that when demand exceeds supply (1)

or

when other methods fail

or

when it is needed

answers in terms of using other forms of renewables is insufficient1

[7]

(a) (i) decreases (to zero)1

resultant force acts in opposite direction to motion

accept air resistance and weight for resultant force

accept resultant force acts downwards

do not accept air resistance increases1

(ii) velocity includes directionorvelocity is a vector (quantity)

1

18

(b) (i) 3.6

allow 1 mark for correct substitution i.e.

½ × 0.05 × 122 provided no subsequent step2

(ii) 3.6 or their (i)1

(iii) 7.2ortheir (ii) ÷ 0.5 correctly calculated

allow 1 mark for correct substitution i.e.

3.6 or their (ii) = 0.05 × 10 × h2

(iv) B1

of 84Aston Academy

(c) range increases up to 45°1

range decreases from 45°

the range is a maximum at 45° gains both marks

for any two angles that add up

to 90° the range is the same gains both marks

the range increases then decreases gains 1 mark1

[11]

(a) (i) produces carbon dioxide / nitrogen oxides

accept greenhouse gases

ignore pollutant gases1

19

that (may) contribute to global warming

accept causes global warming

damages ozone layer negates this mark

accept alternative answers in terms of: sulfur dioxide / nitrogenoxides causing acid rain

1

(ii) carbon capture / storage

answer must relate to part (a)(i)

collecting carbon dioxide is insufficient

or

plant more trees

or

remove sulfur (before burning fuel)1

(b) (i) (power station can be used) to meet surges in demand

accept starts generating in a short time

can be switched on quickly is insufficient1

(ii) can store energy for later use

accept renewable (energy resource)

accept does not produce CO2 / SO2 / pollutant gases1

(c) (i) turbines do not generate at a constant rate

accept wind (speed) fluctuatesaccept wind is (an) unreliable (energy source)

1

of 84Aston Academy

(ii) any one from:

• energy efficient lighting (developed / used)

use less lighting is insufficient

• increased energy cost (so people more likely to turn off)

accept electricity for energy

• more people becoming environmentally aware1

[7]

(a) conduction120

(b) (i) there is a bigger temperature difference between the water and thesurrounding air

accept the water is hottest / hotter1

so the transfer of energy (from hot water) is faster

accept heat for energy

ignore temperature falls the fastest1

(ii) 120

allow 1 mark for converting kJ to J correctly, ie 4 032 000

or

correctly calculating temperature fall as 8°C

or

allow 2 marks for correct substitution, ie 4 032 000 = m × 4200 × 8

answers of 0.12, 19.2 or 16.6 gain 2 marks

answers of 0.019 or 0.017 gain 1 mark3

(iii) water stays hot for longer1

so heater is on for less time

accept so less energy needed to heat water1

so cost of the jacket is soon recovered from) lower energy costs / bills

accept short payback time1

[9]

of 84Aston Academy

(a) 4200

allow 2 marks for correct substitutionie 6930 = 0.330 × c × 5.0

answers of 1050 or 840

or

correctly calculated answer from correct substitution of incorrecttemperature change

or

identification of temperature change ie 5 °Cgain 1 mark

3

J / kg°C

accept J / kg K1

21

(b) (in a metal) free electrons

to gain full credit the answer must be in terms of free electrons1

gain kinetic energy

accept move faster1

(free electrons) transfer energy to other electrons / ions / atoms

do not accept particles1

by collision

allow a maximum of 2 marks for answers in terms of atoms / ions /particles

• gaining kinetic energy or vibrating faster / more

• transferring energy by collisions1

(c) (air) particles spread out1

(which causes the) air to become less dense / expand

do not accept particles become less dense1

(so the) warm air rises

do not accept heat risesparticles rise is insufficient

1

of 84Aston Academy

(d) large surface area

ignore references to type of metal or external conditions1

black / dark (colour)1

[13]

(a) any three from:

• no carbon dioxide emitted (to produce electricity)

no greenhouse gases is insufficient

• doesn’t cause global warmingallow climate change or greenhouse effect for global warming

• nuclear power doesn’t cause earthquakes• more energy released per kg of fuel (compared to shale gas)

3

22

(b) uraniumorplutonium

ignore any numbers given1

(c) a neutron is absorbed by a (large) nucleus

a description in terms of only atoms negates first two marking points1

the nucleus splits into two (smaller) nuclei1

releasing energy (and gamma rays)1

and (two / three) neutrons1

[8]

of 84Aston Academy

(a)

1

m = 1.2 × 2.3 × 104

1

m = 27 600 (kg)

allow an answer of 28 000 (kg) or 2.8 × 104 (kg)

or

m = 2.76 × 104 (kg)1

an answer of 27 600 (kg) scores 3 marks

23

(b) mass of air passing the turbine blades is halved which decreases kinetic energy by afactor of two

1

(wind speed is halved) decreasing kinetic energy by a factor of four1

so kinetic energy decreases by a factor of eight1

allow power output for kinetic energy throughout

(c) 388 000 = 0.5 × 13 800 × v2

this mark may be awarded if P is incorrectly / not converted1

this mark may be awarded if P is incorrectly / not converted

or

or

v2 = 56.21

v = 7.50 (m/s)

an answer that rounds to 7.50 (m/s) only1

[9]

of 84Aston Academy

(a) g.p.e. = mass × gravitational field strength × height

accept Ep = mgh1

24

(b) Ep = 50 × 9.8 × 201

9800 (J)

allow 9800 (J) with no working shown for 2 marks

answer may also be correctly calculated using W = Fs

ie allow W = 490 × 20 for 1 mark

or answer of 9800 (J) using this method for 2 marks1

(c) 7840 (J)

allow ecf from ‘11.2’1

(d) 7840 = ½ × 50 × v2

1

allow for this point

1

17.7(0875) (m / s)1

18 (m / s)

allow ecf from ‘11.3’ correctly calculated for 3 marks

allow 18 (m / s) with no working for 2 marks

answer may also be correctly calculated using v2 – u2 = 2as1

(e) extension = 35 (m) and conversion of 24.5 kJ to 24500 J1

24 500 = ½ × k × 352

1

401

allow 40 with no working shown for 3 marks

an answer of ‘16.2’ gains 2 marks

[11]

of 84Aston Academy

(a) any two from:

• cost per kWh is lower (than all other energy resources)

allow it is cheaper

ignore fuel cost

ignore energy released per kg of nuclear fuel

• infrastructure for nuclear power already exists

accept cost of setting up renewable energy resources is high

accept many renewable power stations would be needed to replaceone nuclear power station

accept (France in 2011 already had a) surplus of nuclear energy, soless need to develop more renewable capacity for increaseddemand in the future

accept France benefits economically from selling electricity

• more reliable (than renewable energy resources)

accept (nuclear) fuel is readily available

ignore destruction of habitats for renewables2

25

(b) any two from:

• non-renewable

allow nuclear fuel is running out

• high decommissioning costs

accept high commissioning costs

• produces radioactive / nuclear waste

allow waste has a long half-life

• long start-up time

• nuclear accidents have widespread implications

allow for nuclear accident a named nuclear accident

eg Fukushima, Chernobyl

ignore visual pollution2

(c) 0.48 (kW)

allow 1 mark for correct substitution

ie 0.15 = P / 3.2

an answer of 480 W gains 2 marks

an answer of 48 or 480 scores 1 mark2

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(d) the higher the efficiency, the higher the cost (per m2 to manufacture)

accept a specific numerical example1

more electricity could be generated for the same (manufacturing) cost using lowerefficiency solar panelsor(reducing the cost) allows more solar panels to be bought

accept a specific numerical example1

[8]

(a) elastic potential126

(b) (i) line is straight

accept line does not curve1

(ii) 400

allow 1 mark for correct substitution of any pair of numbers correctlytaken from the graph e.g.160 = k × 0.40

2

newtons per metre or N/m

if symbols are used they must be correct1

(iii) 300

allow 1 mark for correctly obtaining force on 1 spring = 100N2

(c) 52

allow 2 marks for calculating change in gpe for 1 chin-up as 260 (J)or for 12 chin-ups as 3120 (J)

an answer 4.3 gains 2 marks

allow 1 mark for correct substitution into gpe equation ie gpe = 65 ×10 × 0.4 (× 12)

or

correct use of power equation with an incorrect value for energytransferred

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(a) energy required to raise the temperature of a substance by 1 °C

accept heat for energy1

unit mass / 1 kg1

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(b) (i) 7 140 000 (J)

allow 2 marks for a correct substitution, ie

E = 20 × 420 × 850

provided no subsequent step

850 gains 1 mark if no other mark awarded3

(ii) particles in the air have more (kinetic) energy than the particles in the steel

allow particles in the air have a greater speed.1

steelparticles vibrate (about fixed positions)

1

airparticles move freely

1

(ii) the most energetic particles

accept molecules for particles throughout

accept the fastest particles1

have enough energy to escape from (the surface of) the water1

therefore the mean energy of the remaining particles decreases

accept speed for energy1

as energy decreased, temperature has decreased1

[12]

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Examiner reports

(a) 48% of students scored 2 marks for this question, with 40% scoring 1 mark. Those whoscored 1 mark usually did so for the second blank.1

(b) 94% of students recalled this equation correctly.

(c) 87% of students scored 3 marks for this question. The first two marks in the question werefor the substitution into, and rearrangement of, the equation. The third mark was for acorrect final answer.

(d) 31% of students scored 2 marks for this question. Many students read the change in speedcorrectly from the graph and a range of values, between 1.2 and 1.5 m/s, were accepted.The percentage increase in speed proved more challenging as students were often unsurewhether they should have divided by the 9.5 (m/s) or the 11 (m/s). Students who did[((11.5/9.5) − 1) × 100] calculated correctly, scored both marks.

(e) This question differentiated well, with 44% of students scoring 2 or more marks and 49% ofstudents scoring at least 1 mark. Very few students scored 3 marks. The decrease in speeddue to additional work done or the increased gravitational potential energy were often seen.Many students thought that the cyclist should increase their power output when cyclinguphill, although the question was asking about their maximum speed.

(a) This question was quite well answered by around half of the students.

(b) The majority of students seemed unfamiliar with the term ‘decommissioning’.

(c) Around three-quarters of students scored at least one mark. There was evidence that somestudents had not taken on board that the question referred to ‘companies generatingelectricity’, as their answers referred to ‘energy saving appliances’ or ‘switching lights off’.

(d) Under half of the students were able to score at least one mark, with only a small numberof responses scoring all three marks. Common errors were to talk about ‘electricity’ beinglost in the cables, or ‘no energy will be lost’.

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In part (a)(i) very many candidates correctly wrote down two environmental problems, the onlydistractor for a few being that coal was non-renewable and so reserves should be conserved. Inpart (ii) there were many correct answers but a number of candidates lost marks where answerswere not sequential to their answers in part (i). A few candidates tried to filter out sulphur dioxideor one of the carbon oxides and so failed to gain the mark. Part (b) proved to be more difficult. Inpart (i) a small number of candidates introduced the voltage, 23 500 V into their calculations andso arrived at the wrong answer. Some candidates did the energy calculation expected in part (ii)at this point. Part (ii) was well answered, the main mistake being to copy the calculator answersof 4.86487414, this did not gain the mark. answers have to be in standard form or written outcompletely. Candidates were not penalised for eight digit answers. In part (iii) the efficiencyequation was well known, substitution into it was correct and any correct result was credited from100% down to low negative powers of ten, such answers resulting from mistakes earlier in thequestion. In part (c), (i) was well answered by the vast majority of candidates and most went onto score at least one mark in part (ii), the mark commonly lost being that for the idea of wastedenergy being diluted and therefore not much use.

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(a) (i) Almost half of students scored a mark by identifying infra-red radiation. Commonincorrect answers were ultra-violet, visible light or the Sun.

(ii) Many good answers were seen, with about a quarter of students scoring all 3 marks.A number of students thought that water evaporates to form steam which is incorrectand therefore negated the first marking point. A minority of students thought thatwater turned the turbine which negated the first and second marking points. Somestudents thought the turbine generated electricity negating the third marking point.

(b) (i) Almost a third of students understood that a high specific heat capacity meant lots ofenergy could be stored. Most incorrect answers referred to the salts melting (theywere already molten) or changing state, which was insufficient.

(ii) The majority of students gained 2 or 3 marks for this question. The most commonmistake was to incorrectly round their answer to 15 or to ignore the instruction aboutsignificant figures and give an answer of ‘15.7’ or a similar un-rounded figure.

(iii) Many students failed to realise that the table for this part question held the informationneeded to answer it. Many students thought that the weather or other associatedproblems were responsible, when in fact summer is the only time when the powerstation can operate at maximum capacity because of the highest power per m2 andthe longest number of daylight hours. Some students answered with the expectedresponse that the power varies and so do the number of daylight hours, but thesewere few.

(c) (i) Most students scored the first marking point, comparing the Capacity Factor forrenewable with non-renewable sources. Many scored the third marking point for theunreliability of non-renewable sources.

Few students scored the 2nd marking point for stating that non-renewable fuels werealways available. Many students just stated that non-renewable sources were reliablewhich was insufficient.

(ii) Very few students scored this mark. The idea that for the Capacity Factor to be higherthe solar storage power station was generating electricity for more time was needed.It was insufficient to say that the Sun is reliable or it is in a hot desert or that it storesenergy.

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This question produced many pleasing answers, candidates making a choice and then givingreasoned arguments for their choice. However some interpreted the question as ‘Writeeverything you can about coal fired power stations, wind turbines and hydroelectric schemes’.Such candidates were unable to score full marks on the mark scheme. A few chose thehydroelectric scheme and proceeded to generate power on the lake, river and coastal waters,skipping from one to the other with ease.

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Part (a) caused only minor problems with the most common error being the use of ‘potential’energy in the upper energy transfer box.

Most candidates made a reasonable attempt at part (b), although in part (ii) it was rare to see asupporting statement or comparison linked to the stated advantage. Most candidates wereprepared to list multiple advantages rather than support or explain one advantage.

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(a) This question was generally well answered though some candidates had misread the keyand confused hydro with oil. Some candidates only gave a simple response about thedecrease in oil and had not read the question well enough to spot that it contained a plural.

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(b) (i) Surprisingly only just over half of the candidates could correctly name the process.Most incorrect answers gave the name of a chemical process.

(ii) Only the better candidates were able to gain full credit for a clear explanation of theprocess. Many candidates failed to gain any credit for omitting the word ‘steam’and/or giving descriptions of ‘heat’ turning turbines. Some candidates tried gave anexplanation of nuclear fission, clearly having not read the question.

(iii) Few candidates gained both marks. The majority gained one mark for stating a ‘noCO2 released’ type answer or that nuclear power stations are reliable. The mostcommon incorrect responses were ‘nuclear fuel is efficient’/ ‘nuclear fuel will not runout’/ ‘nuclear fuels produce more energy’/ ‘nuclear fuel is renewable’. A worryingproportion of candidates talked about burning the nuclear fuel.

(iv) This was well answered with the majority of candidates knowing that the waste wasradioactive. Extra information was often given such as the effect on tissue, foodchains, etc and the long half-life. Weaker responses referred to the waste as reactiveor were concerned with greenhouse gases or acid rain.

(c) Many good answers were seen. The second mark was often lost because of a reference toCO2 destroying the ozone layer or simply repeating the given phrase ‘climate change’.

In part (a) those candidates who chose the payback route generally gained no credit, unless theypicked the boiler as the best option. Many candidates scored two marks for selecting the boilerand a correct calculation. A significant number of candidates scored all three marks forcompleting all the calculations correctly and making the correct choice.

Few candidates scored 2 marks in part (b). Most candidates failed to link the less energy back tothe power station. The common mark scored was for stating the reduction in fuel burnt. Manyconsidered the efficiency of the bulbs; but did not link it back to the need to generate lesselectricity. Very few thought about the need for fewer bulbs and the energy saving in theirmanufacture. There were a significant minority of candidates who thought that conventional lightbulbs emit carbon dioxide or that energy loss somehow produces carbon dioxide, often as aresult of heat loss.

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(a) Nearly four-fifths of candidates scored both marks for this part question. Where errorsoccurred they were often slips – removing or adding a 0 from the working out to the answerline, stating 12 squared in the working out but not carrying out the function on thecalculator. Other candidates divided the correct answer by 20 or chose to convert kilogramsto grams.

(b) Candidates did not seem to understand the need for some quantitative detail, with manysimply referring to a greater or more area. Many candidates considered the actual area ofthe blades rather than the area swept out by the blades.

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In part (a) few candidates gained full credit. A significant number of candidates had hydrogenand helium reacting or fusing together with further confusion between the terms fusion andfission. Some candidates thought the Sun produced energy from combustion. A further commonerror was to answer entirely in terms of how the Sun provides energy to the Earth. Pail (b)(i) wasanswered well with most candidates scoring both marks. Pail (b)(ii) was generally answered well,although some candidates made the same point about the uncertainty of the wind in threedifferent guises.

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Part (a) was not well answered with almost 50% of candidates scoring no marks. Manycandidates wrote negatively about fossil fuels rather than about the merits of nuclear fuel. Therewere many vague comments about a lot of energy, with the stronger candidates being able torelate this to the amount of fuel being used. Some candidates wrote about reliability but some didnot gain credit due to the vagueness of their answers.

The vast majority of candidates gained no credit in part (b) most ignored the fact that the wastewas buried deep, or that it would be in any way contained.

In part (c) some candidates did not use the information they had been given and others ignoredthe question’s emphasis on the power companies. Many candidates did not distinguish betweenbiofuels and electricity, thinking the power company would be selling the biofuels. The idea ofcarbon neutral was well identified by stronger candidates, but the weaker ones did not appear tobe aware that burning biofuels also gives rise to carbon dioxide emission. A large number ofcandidates (40%) were unable to use any of the information presented to them and gained nocredit at all.

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(a) (i) There were few correct answers, most candidates referred to closing down the powerstation but few discussed the removal of radioactive material from the site.

(ii) A mix of answers with many candidates attempting to give a reason.

(b) (i) A large number of answers failed to mention the efficiency, which is what the questionwas about. Of those candidates which did, some compared the efficiency of the threepower stations to each other, some discussed the change in efficiency of each powerstation over the years, but very few gave both answers.

(ii) A large number of vague answers were seen, such as ‘anything could happen in thefuture’ or ‘we can’t predict that far into the future’. Just over half of the candidatesscored at least 1 mark.

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(a) The term ‘nuclear fission’ was well known. However, it is alarming how many students thinkthat nuclear fuels are burned in order to release energy. The process of generatingelectricity was not well described; many students seem to think that it is the turbine thatgenerates the electricity. An advantage of nuclear fuels ‘reliability’ was often given.However, many students spent a lot of time and filled a lot of space describing numerousdisadvantages of nuclear energy and / or the advantages and disadvantages of wind withno reference at all to nuclear energy.

(b) Nearly a fifth of students did not attempt this question. Many students simply repeated thestem of the question and had no idea about the storage of the carbon dioxide following its‘capture’. A common error was the assumption that ‘carbon capture’ involves the removalof the existing carbon dioxide from the atmosphere.

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(a) This question was well done with nearly all of the students scoring both marks.

(b) This question was not well answered for a variety of reasons. Some students simply did notknow where to start, whilst others tried using momentum. Also, many realised the need touse the equation for kinetic energy, but were then unable to transform it or failed to squareroot; 300 was a common incorrect answer. Few students stated that GPE = KE althoughthey used their answer from part (a) in the calculation. Only a tenth of students were able tocomplete the calculation and give an answer with an appropriate number of significantfigures.

(c) Most students scored one mark for mentioning friction, but very few students were able togive a complete explanation to score all three marks. The idea that work would be doneagainst friction was hardly ever mentioned. A significant number of students thought thatthe reduced maximum speed was due to the change in angle of the slide and the slidebecoming horizontal.

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(a) Students made heavy weather of this calculation, often converting the time into seconds,and failing to realise that the 5600 kilowatt-hours was the energy rather than the power.Hence very large values (several hundred thousand), obtained from these calculations,were quoted as being the wind speed. Even students who correctly calculated the poweroutput as 1400kW often seemed unable to relate this to the graph to obtain acorresponding wind speed.

(b) (i) As with a similar question in last year’s paper, very few correct responses were given.Transformers rarely featured, but many students seem to think that pylons carryelectricity.

(ii) Many students knew that transformers were involved here, but answers were oftennot specific enough, for instance ‘step up and step down transformers are used’.

(c) Again, answers often failed to be specific enough, for example ‘use another way ofproducing electricity’. A significant number of answers referred to using wind turbines,indicating that students had not read the newspaper extract carefully.

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(a) (i) Nearly two thirds of the students scoring zero. Some students had the idea of theweight and air resistance combined being greater than the upward force, but thenfailed to mention the direction of the forces so missed out on the second mark. Veryfew students used the term ‘resultant force’ but when it was used it was more oftenused to explain an increasing speed, suggesting that the students couldn’t believethe rocket was getting slower as it went up. Unfortunately, many students stated thatair resistance would increase and hence would start to push down on the rocket andreduce its velocity.

(ii) Nearly three quarters of the students scored this mark, most giving a clearexplanation of the directional difference between speed and velocity.

(b) (i) Just over three quarters of the students scored both marks, a great improvement onsimilar calculations in previous years.

(ii) Many answers seemed to be spontaneous, incorrect and obscure numbers. Many ofthe students clearly did not understand that the command word ‘state’ in an examquestion means that no calculation was required. Many students wrote 36 for thisanswer, omitting the decimal place, and then correctly used 36 in the final part of thequestion, getting an answer of 72 m instead of 7.2 m.

(iii) This was poorly done with half of the students scoring zero. A small number ofstudents made a fresh start with this part question and scored both marks forcorrectly calculating 7.2 m, despite having gained no marks for the first two parts ofthe question.

(iv) Surprisingly, only half of the students scored this mark.

(c) About one third of the students scored both marks. Many students who stated a patternwrote that “the greater the angle the greater the range” but did not comment on whathappened after 45 degrees and so scored zero. Those who did not state a pattern justpicked out a couple of angles and commented on the range for those angles specificangles i.e. ‘big’ or ‘small’. A significant number of students wrote about the relationshipbetween height and range or angle and height, instead of angle and range.

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(a) (i) This was generally well answered with over half of the students scoring both marks.The most common answers were related to carbon dioxide and global warming.

(ii) There were some good answers describing carbon capture methods. However, asignificant number of students failed to take notice of the statement that ‘the amountof fossil fuels burnt stays the same’ and gave answers relating to reducing theamount of fossil fuels burnt.

(b) (i) This was well answered by over half of the students. A common error was to statewhat a ‘short start-up time’ was, rather than explaining its importance.

(ii) Over half of the students scored the mark here, the most common answer being‘renewable’, with a minority realising the significance of it being a way to store energyfor use at a later time.

(c) (i) This was well answered by nearly two-thirds of students. It appeared that a significantnumber of students did not understand the word ‘fluctuations’.

(ii) Again this was well answered, the most common response referring to the increaseduse of energy saving light bulbs.

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(a) Nearly three quarters of the students correctly identified the process of conduction.

(b) (i) Fewer than one fifth of the students realised that this question related to the greatestdifference in temperature between the water and the surroundings.

(ii) A small minority of the students scored full marks. The majority of students failed toconvert kJ to J. Many students were unable to transpose the equation correctly.

(iii) This was very well answered, with over half of the students scoring at least two of thethree marks. This was usually for realising that the insulating jacket would keep thewater hotter for longer, thus requiring the heater to be switched on for a shorterperiod of time. Many did not score the third mark because they merely repeated thequestion by saying that this ‘saves money’ rather than referring to the cost ofelectricity / energy used.

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(a) This question was well answered with over half of students scoring 3 or 4 marks. Theincorrect use of a calculator caused most problems, with the absence of brackets aroundpart of the calculation, which resulted in an answer of 105 000. This would have gained 1mark only for the temperature change being identified. A difficult unit, but many studentshad either learned it or worked it out from the information given in the question.

(b) Students found this question difficult with only a small minority of students scoring 3 or 4marks. Lots of incorrect physics was seen which negated some marking points, electronsvibrating, rather than gaining kinetic energy or moving faster, for example. For studentswho described conduction by describing vibrations of atoms (or ions) a maximum of 2marks was available. However, credit was given to students who made correct statementsabout both parts of the conduction explanation. Some students described the energygained as ‘heat’ which is incorrect at an atomic level. If students failed to mention that theelectrons were free, they were limited to scoring 3 marks.

Many answers were seen in which ‘cold’, ‘cold particles’ or ‘cold energy’ were beingconducted. Some reasonable but incomplete answers were given in terms of ‘particles’; insuch answers, a common mistake was to say that the particles would start to vibrate whengiven energy. Whilst a large number knew that conduction through metals involved ‘freeelectrons’, it was obvious that many did not understand the role which these played. Manyanswers gave a description relating to ‘particles’ then added that ‘free electrons also helpthe energy to be conducted’, without further explanation.

(c) Students found this question difficult with only a minority scoring 2 of the 3 marks available.Students who only discussed the air were generally more successful, gaining 2 marks forthe idea that the warmed air becomes less dense and rises. Students who started theiranswer by talking about particle separation (first marking point) usually negated the secondmarking point by incorrectly describing particle density changing, then ‘warmer’ particlesrising, which was insufficient for the third marking point; as convection is a bulk process itwas necessary to say that the warmer air rises.

(d) Almost half of the students scored 1 mark. Many students referred to a large surface area,but there was confusion amongst some students relating to the colour of the cooling fins,many opting for ‘light and shiny to reflect the heat away’.

Any reference to external conditions was insufficient - temperature difference, for example.Fans were ignored as separate from the fins, as was the amount of air flow. Large surfaceto area volume was accepted also, but ‘thin’ was insufficient. Some students stated factorslike ‘surface area’ without describing it as ‘large’ or ‘small’, etc.

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(a) 11% of students scored 3 marks, 27% of students scored 2 marks. Lots of thoroughanswers were seen, but they needed to state the advantages of nuclear, rather thandisadvantages of shale gas. ‘Shale gas releases CO 2’ did not score a mark, but ‘nucleardoes not release CO2’ did score a mark. Information about shale gas was given in thequestion, which is why these answers were insufficient for a mark.

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(b) 66% answered this question correctly. The most common correct answer was uranium. Acommon incorrect answer seen was oil.

(c) Many good answers seen with 12% scoring 4 marks and 20% scoring 3 marks. Somestudents didn’t mention the nucleus absorbing the neutron or the nucleus splitting in two, sothey didn’t score the first two marking points. The first marking point was the least likely toscore. The third marking point was scored by most students.

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(a) 87% of students scored 3 marks. Some students rearranged the equation incorrectly andthen substituted, scoring 0 marks.23

(b) This was a conceptually demanding question. 13% of students scored 1 mark, usually forthe idea that halving the wind speed decreased the output by a factor of 4.

(c) A challenging grade 8-9 calculation. 30% of students scored 3 marks. A few studentsscored 1 mark for the substitution, whether they converted the power to watts or not.

(a) This question was well answered with half the students scoring 1 mark and a third ofstudents scoring 2 marks. The most common correct answers referred to the cost per kWhand the economic benefits, 'France can sell their excess electricity to other countries' typeof statement. Insufficient responses included 'it's cheap', which wasn't comparative; orreferences to no CO2 released, as the renewables mentioned don't release CO2 either.Reliability was another commonly seen response, which was creditworthy.

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(b) Just under a third of students scored 2 marks for this question. Answers that wereinsufficient were 'dangerous', or 'radiation may leak'. Naming nuclear accidents wasinsufficient for a mark, the idea of widespread or major implications was necessary too.Commissioning or decommissioning time was insufficient as the question was aboutgenerating electricity, so while the cost was an issue, time was too vague. A number ofstudents thought that 'nuclear is a fossil fuel so contributes greatly to global warming',which is clearly incorrect.

(c) Three fifths of students scored 2 marks for this question. Some students incorrectlymultiplied their answer by 100(%) and got an answer of 48, which scored 1 mark, ormultiplied the power in W by 0.15 and got an answer of 480, which also scored 1 mark.

(d) Three fifths of students scored 1 mark for the idea that higher cost meant higher efficiencysolar panel, quite a lot of students also scored 1 mark for the idea that if cheaper, morewould be bought. Many students, however, incorrectly thought that if you purchased alarger number of solar panel C, the overall efficiency would increase. These students arelikely to have scored a maximum of 1 mark for the idea that more could be bought,depending how they worded their answer. Only a tenth of students scored 2 marks for awell-reasoned answer e.g. The more efficient solar panels cost more, but you could buymore solar panel C for £40, that would generate more electricity than 1 solar panel A.

(a) Over half of the students got this correct although some students gave two types of energyrather than one type comprising two words.26

(b) (i) Only just over a third of the students scored this mark. The most common incorrectanswers were references to the graph being directly proportional rather thandescribing the graph line itself as straight or having a constant gradient. Manystudents said 'the line is constant'.

(ii) A quarter of the students scored all three marks with a further half of all studentsgaining 2 marks. Students could identify correct points from the graph but weakerstudents struggled with rearranging the formula to change the subject to k. Somestudents attempted to take values from the graph but didn't read the graph correctlyand wrote values down such as 0.5 instead of 0.05. A significant number of studentsincorrectly used the equation Work = F x d. Incorrect units were mostly Nm orreversed m/N, or not capitalised n/m, with a variety of other incorrect options eg N, W,J, or nothing. A few students correctly gave the answer as 4 N/cm.

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(iii) A third of the students scored both marks and a further third scored one mark. Somestudents correctly extrapolated 100N from the graph but then did not take intoaccount the fact that there were 3 springs so did not multiply by 3 and therefore onlyscored 1 mark.

(c) Two thirds of the students scored some marks on this question, although fewer than a fifthscored full marks. Most students were able to calculate the energy required for one chin up,but did not take into account that they were being asked about 12 chin-ups. Some studentswere able to gain a compensation mark by clearly showing that they were dividing anincorrect energy by time to work out the power.

(a) The definition of specific heat capacity was well known, with nearly two-thirds of studentsgaining both marks. A small minority achieved one mark, either failing to specify a mass of1 kg or a rise in temperature of 1 °C. A common error was to attempt to define latent heat.

(b) (i) This calculation was very well answered with almost all students scoring all threemarks. Few gained two marks, usually for substituting into the correct equation, butfailing to perform the calculation correctly. Another common error was to use the finaltemperature instead of the change in temperature.

(ii) Around a third of students gained all three marks, with a further third scoring twomarks and around a fifth scoring one mark. Whilst most students attempted todescribe the movement of the particles, many failed to address the comparison ofenergies. Of those who failed to gain a mark, many appeared to answer a differentquestion - for example comparing the particles in the steel at high and lowtemperatures or comparing energy transfer in solids and gases.

(iii) More than one-quarter failed to score any marks, with just over 10% achieving all fourmarks. Most did not refer to the reduction in the mean energy of the remainingparticles and how this links to a fall in temperature. Despite the question saying‘explain in terms of particles’, many answers were seen which made no reference toparticles at all − this is an example of a situation where it would benefit students tohighlight key words in the question.

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236 minutes 234 marks - ASTON ACADEMY GCSE PHYSICS

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Transcript of 236 minutes 234 marks - ASTON ACADEMY GCSE PHYSICS