PHYSICS - eduBuzz.org · A car's speed is recorded over a period and the results are show in the...

Clackmannanshire Physics Network

Physics

National 4 & 5

Dynamics & Space

-----

Homework Exercises

LAPD:2013 Clackmannanshire Physics Network

Dynamics & Space - National 4 / 5

Homework Exercises

Summary

Homework 1: Speed

- Average speed

- Instantaneous speed

Homework 2: Vectors and Scalars

- d, s, v, v, etc.

Homework 3: Speed-time graphs & Acceleration

- Using and plotting speed-time graphs

- Calculating acceleration

Homework 4: Velocity-time graphs & Acceleration

- Acceleration

- Positive and negative displacements

Homework 5: Forces I

- friction, W = mg, F=ma,

- balanced and unbalanced forces

Homework 6: Newton’s Laws II & Work Done

- Newton 1 and 2

- Open ended question

Homework 7: Projectiles

- vertical and horizontal calculations

- v-t graphs

Homework 8: Space

- Astronomical terms, satellites

Homework 9: Work Done, Potential and Kinetic Energy

- EW, EP, EK

- Open-ended question

Homework 10: Heat Energy

- EH = c m ΔT, EH = m l

Homework 11: Cosmology

- Line spectra

- The Big Bang Theory



Homework Exercises

B

A

Homework 1 – Speed

1. David can run 400m in a time of 50 seconds. Calculate his average speed. (3)

2. If a car is travelling at a constant speed of 8m/s, how far will it travel in 2 minutes? (3)

3. If you were trying to find the average speed of a car travelling down the road.

(a) What measuring equipment would you use? (1)

(b) What measurements would you make? (1)

(c) What calculations would you carry out? (1)

4. During a physics lesson Andy tries to calculate Graeme’s instantaneous speed when

running by timing how long it takes him to cross a line.

He uses a stop clock to measure the time.

(a) Explain why this method will give poor results for the instantaneous speed. (1) . (b) Suggest the equipment needed to make the experiment more accurate. (1)

5. A trolley (with a card attached) was allowed to run freely down a track, as shown in the

diagram.

Light gates positioned at A and B were connected to electronic timers and the time to

pass each gate was measured.

The following readings were obtained:

Time at A: 0.080 s

Time at B: 0.050 s

Length of card = 5cm

Calculate the increase in speed between points A and B (5)

6. You are standing next to a railway track and you want to estimate the speed of a

train you see approaching. The train consists of six motorised carriages and you

estimate that each carriage is 25m long. Using the stopwatch function on your

mobile phone you find that it takes 2.5 seconds for the train to pass you.

(a) Calculate the speed of the train. (4)

(b) How would the train driver find out his instantaneous speed at this point ? (1)



Homework Exercises

7. Read this passage on ‘Thinking and Braking’ and then answer the questions that

follow.

“You are travelling at 30 mph in a car in good road conditions when you suddenly see children crossing the road. In the time taken for you to react and then apply the brakes to stop the car, you will have travelled a total distance of 23 m. If the car had been travelling at 60 mph the total stopping distance would have been 73 m.

The stopping distance consists of two parts: the thinking distance and the braking

distance.

thinking distance = speed x reaction time

Reaction times vary from person to person. An average driver has a reaction time of about 0.8 seconds. A professional racing driver has a reaction time of about 0.2 seconds. Your reaction time is likely to be much longer if you have taken drugs or alcohol. Even a small amount of alcohol can greatly increase your reaction time.”

(a) What is meant by the term ' thinking distance'? (1)

(b) What will happen to the thinking distance if the car is going faster? (1)

(c) If a car is going faster will the reaction time alter? Explain your answer. (2)

Total 25 marks

==== End of Homework 1 ====



Homework Exercises

Homework 2 – Vectors & Scalars

1. (a) Give an example of a scalar and a vector.

(b) Explain the difference between a scalar and a vector. (2)

2. During a training session Jessica sprints along a track for a distance of 80m in a time of 10s. She then

turns round and jogs 40m back towards the start in a time of 15s.

(a) What is the total distance travelled by Jessica? (1)

(b) What is her average speed? (3)

(c) What is the magnitude of her total displacement? (1)

(d) Calculate the magnitude of her average velocity. (3)

If Jessica now walks back to the starting line...

(e) What is the magnitude of her total displacement now? (1)

(f) What is the magnitude of her average velocity for the whole exercise. (1)

3. If a man walks 400m East and then 300m North...

(a) What distance has he travelled? (1)

(b) Calculate his displacement. (3)

4. During a race, the wind is blowing Ben’s sailing dinghy to the South at a

velocity of 12ms-1.

The tidal current in the water is 5ms-1 to the East.

Calculate the resultant velocity of Ben’s boat. (3)

12 ms-1

S

300m N

400m E

5 ms-1

E



Homework Exercises

Homework 2 – Vectors & Scalars (continued)

5. During an orienteering race a runner runs 400m North, 400m West and 400m South in a time of 5

minutes.

(a) Calculate her average speed. (3)

(b) Calculate her average velocity (3)

Total 25 marks


500m N

400m W

500m S



Homework Exercises

40

30

20

10

speed (m/s)

Time (s) 5 10 15 20 25 30

B C

D

speed (m/s)

time (s) 10 20 30 40 50

40

A

30

20

10

speed / ms-1

time / s 2 4 6 8 10 12 0

30

24

18

12

6

0

Homework 3 – Speed-time graphs and Acceleration

1. The speed of a glider which was cruising at a steady speed before going into a dive is

shown in the graph.

(a) What was the speed of the glider before the

dive? (1)

(b) What was the speed of the glider after diving

for 15 seconds?

(1)

2. A car's speed is recorded over a period and the results are show in the table below:

(a) Plot a graph of the car's motion over this 10-second period. (2)

(b) From the graph, find the car's speed 5 seconds into its journey. (1)

(c) Describe the car’s motion over the 10 seconds.

(1)

3. Look at the graph. This shows the speed of a car over a short journey. Use the graph

to answer these questions.

(a) Describe the car’s motion between:

A and B;

B and C;

C and D.

(b) Estimate the car’s speed after 10

seconds. (1) 0) (1)

(c) Calculate the distance travelled by the car between A and B (3)

(d) Calculate the acceleration of the car between A and B (3)

TIME (s) SPEED (m/s)

0 0

2 6

4 12

6 18

8 24

10 30

(3)

(1)

(1)

(1)



Homework Exercises

speed / ms-1

time / s 10 20 30 40 50

8

6

4

2

Homework 3 (continued)

4. Calculate a car’s acceleration if its speed increases by 12 m/s in a time of 3 s. (3)

5. Derek runs away from a wasp and he accelerates from rest to 5 m/s in a time

of 1.25 seconds.

Calculate his acceleration. (3)

6. A hot air balloon is released and it accelerates upwards. During the ascent, some

sandbags are released and the acceleration increases. The graph shows its vertical

motion during the first 50 seconds of its flight.

Calculate the height at which the sandbags were released (3)

Total 25 marks


30

2



Homework Exercises

Homework 4 – Velocity-time graphs and Acceleration

1. At the start of a race, a sprinter accelerates to a velocity of 10ms-1 in a time of 4s.

Calculate the acceleration of the athlete. (3)

2. A hot air balloon is released and it accelerates upwards. During the ascent, some

sandbags are released and the acceleration increases.

The graph shows its vertical motion during the first 50 seconds of its flight.

(a) Calculate the acceleration after the sandbags are released. (3)

(b) Calculate the displacement of the balloon after 50 seconds? (3)

Velocity/ms-1

Time/s 10 20 30 40 50

8

6

4

2

30 20 20

4 2 2



Homework Exercises

Homework 4 – Velocity-time graphs and Acceleration (continued)

3. The graph shows the velocity of a high powered dragster car during a competition.

The car completed the race in 8 seconds.

(a) Calculate the displacement of the car during the race. (3)

(b) Calculate the car’s acceleration after it had crossed the finish line. (3)

Velocity (ms-1)

Time (s)

1 2 3 4 5

80

60

40

20

6 7 8 9 10 11 12

2 6

40

40

6

40



Homework Exercises

Homework 4 – Velocity-time graphs and Acceleration (continued)

4. If Sally’s BMW accelerates from rest at 10 m/s2, what velocity will she be doing

after 3 s ? (3)

5. The graph shows the velocity of a trolley on an inclined track, during an experiment

in the Physics class.

(a) Calculate the acceleration of the trolley during the experiment. (3)

(b) Calculate the displacement of the trolley during the experiment. (3)

(c) Describe what happened to the trolley after 2s. (1)

Total 25 marks


velocity (ms-1)

2

1

0

-1

-2

1 2 3 4 time (s)

2

2

1.5

1.5



Homework Exercises

Homework 5 – Forces I

1. (a) A force can deform an object and so change its shape.

A force can also accelerate an object and so change its A and/or the B ,

in which it is moving. Which word best replaces A and B?

(2)

(b) A tennis player applies a force on the ball with his racquet. Give

one effect on the ball that proves a force has been applied. (1)

2. What value of gravitational field strength is used to calculate weight at the surface

of the Earth? Don’t forget to include a unit in your answer. (1)

3. The table below gives the gravitational field strength for the other planets in our

solar system. Using information in this table, answer the questions.

PLANET g (N/kg)

Mercury 3.7

Venus 8.8

Mars 3.8

Jupiter 26.4

Saturn 11.5

Uranus 11.7

Neptune 11.8

(a) Find the weight of a 60 kg robot on Mercury. (3)

(b) Find the mass of a woman who weighs 1188 N on Jupiter. (3)

Turn over ……….



Homework Exercises

Homework 5 – Forces I (continued)

4. (a) If an object is moving forwards, in what direction will the force of friction act? (1)

(b) What type of energy is produced when there is friction between a car’s brake

discs and its brake pads? (1)

(c) State another example of where friction is helpful and we try to increase it. (1)

(d) Give an example where we try to reduce friction as much as possible. (1)

5. (a) Newton’s First Law of Motion in about ‘balanced forces’. What are balanced

forces? (1)

(b) If the forces on an object are balanced it can either stay at rest or do what? (1)

6. (a) Newton’s Second Law of Motion in about ‘unbalanced forces’. What do unbalanced

forces cause? (1)

(b) Write Newton’s 2nd Law as an equation. (1)

(c) List the proper science units for the things in the equation you have just written. (1)

7. Katie slides down a chute at a leisure centre. If her mass is 45kg, and her acceleration is

2 m/s2, find the unbalanced force acting on her. (3)

8. A car's engine applies a force of 3000 N, and this accelerates it at 4 m/s2. Calculate

the mass of the car. (3)

Total 25 marks




Homework Exercises

Homework 6 – Forces II & Work Done

1. (a) Femi is trying to describe herself standing in the centre of a scrum in a rugby

game. She states that if she is not moving to either side then it’s either because

there are no forces pushing against her, or there are equal forces. This was not the

sharpest thing to say. Draw two diagrams, one showing two equal forces acting on a

body, and another separate diagram showing equal and opposite forces. Use 2.4kN

for each of the forces. (2)

(b) For each of your diagrams above state what would happen to the body. (2)

(c) Later Femi states “it’s only if the forces aren’t equal that you get movement”.

Explain why this isn’t the best statement to make if you’re trying to teach people

about Newton’s Laws. (1)

2. A driver is involved in an accident when driving home from the gym. The car hits a

low wall head on while travelling at 30 mph in a straight line. Explain the next few

seconds if:

(a) the driver is not wearing a seatbelt and the car has no airbags.

(b) he has remembered to buckle up, and the airbags work properly.

You must mention the forces in each case. (4)



Homework Exercises

3. Calculate the acceleration of the following 4kg objects:

(a) (b)

(c) (d) (6)

8 N

8 N 8 N

8 N

8 N

8 N

16 N

16 N

8 N

8 N

16 N

8 N 16 N



Homework Exercises

Homework 6 continued – Forces II & Work Done

4. The diagram below illustrates the horizontal forces acting on a motorbike. The

combined mass of the bike and rider is 125 kg.

(a) Calculate the unbalanced force acting on the bike. (1)

(b) Calculate the acceleration of the bike. (3)

5. Calculate the work done by a team of huskies when they use a force of 800 N to pull

a sled a distance of 1500 m. (3)

6. {Open ended question}. You regain consciousness after an accident in deep space.

Unfortunately, you are 5m away from your ship which is at rest with no-one else on

board. Fortunately, you have a plentiful oxygen supply, a ballpoint pen, a ball of

heavy-duty string, a sharp flick-knife, and some strong sticky-tape in your pockets.

You also have a hammer and some large tools on your utility belt. Use your

knowledge of physics to make a plan to save yourself. You must mention the forces

which will act and how you think they will help you.

(3)


Total 25 marks

200 N 700 N



Homework Exercises

Homework 7 – Projectile Motion

1. A pupil videos a coconut as it rolls horizontally at 2 m/s off the edge of a piece

of classroom furniture. He then uses video analysis software which shows how the

position of the fruit changes with time. The software is made to record the position

as it left the surface and then every 0.1s after that to produce the dots which are

on his picture. He then prints off the picture and rules a vertical and a horizontal

line through each dot as shown below.

(Ignore air resistance for these questions) (a)If the coconut hit the floor just as the last dot was produced, then how much time

did it take to hit the ground? (1)

(b)Are there any horizontal forces on the coconut during its flight? If so name them. (1)

(c)What was the coconut’s horizontal speed at the end of its fall? (Ignore air resistance) (1)

(d)How far did the coconut travel horizontally during its fall? (3)



Homework Exercises

(e)Are there any vertical forces on the coconut during its flight? If so name them. (1)

(f) Describe the coconut’s vertical motion in words (1)

(g) Show that the coconut’s vertical speed is 6.9 ms-1 at the end of its fall? (3)

(h) Draw a graph of the horizontal speed

(y-axis) against time (x-axis) for the whole motion. (3)

(i) Describe the coconut’s horizontal motion in words (1)

(j)What is the area under the vh-t graph? (3)

(k)Draw a graph of the vertical speed (y-axis)

against time (x-axis) for the whole motion. (3)

(l)What is the area under the vv-t graph?

(m)How high was the piece of furniture? (1)

Total 25 marks


8

6

4

2

vertical speed (m/s)

Time (s)

0.1 0.2 0.3 0.4 0.5 0.6 0.7



Homework Exercises

Homework 8 – Space

1. Why is the underside of the space shuttle fitted with special heatproof tiles? (1)

2. (a) What is the purpose of the curved reflector? (1)

(b) Copy this diagram and complete it to show how the curved reflector in a

transmitter helps produce a parallel beam of microwaves: (2)

3. The period of a geostationary satellite is 24 hours.

(a) Explain what a geostationary satellite is. (1)

(b) In satellite communication, what is meant by the word period? (1)

(c) How is a satellite’s period affected by its height above the Earth? (1)

4. Match the following term with a description. Write them together in your jotter. You

don’t have to write the extra clue in brackets. e.g. The universe is all of physical reality. (6)

Term Description

(Mars has two but Mercury and Venus have none).

(There are 8 of these).

(Otherwise known as planetary systems).

(It produces vast amounts of energy by nuclear fusion at some time in

its life).

The Universe ALL of physical reality.

(Nothing physical is outside this; no empty space, nothing).

A planet outside our solar system

(It has a supermassive black hole at its centre).

5. Copy and complete the following table: (3)

Source Time taken for light to reach us on Earth

Sun

Next nearest star

Farthest point in known universe



Homework Exercises

6. What is the definition of a light year? (1)

7. A geostationary satellite orbits at 36,000 km above the Earth’s surface. Calculate

the minimum time it would take to transmit at signal to it from the surface and to

relay the signal to another point on the Earth’s surface. (4)

8. Give 2 uses of satellites and for each one indicate how they have affected our world. (4)

Total 25 marks




Homework Exercises

Homework 9 – Work Done, Potential & Kinetic Energy

1. (a) If there are 46 risers on the stairs between the

bottom floor of the school and the top, calculate the

height of the drop in metres. Assume the riser height

for each step is 16.5 cm. (1)

(b) If a person climbs the stairs, against which force will they have to do work? (1)

(c) Calculate the weight of a 65kg person who climbs the stairs

(You may assume she or he is on the same planet as you). (3)

(d) Calculate the work done in joules by the 65kg person who climbs the stairs. (3)

(e) What is the increase in potential energy of the 65kg person? (1)

2. A £2 coin is lifted from zero height to a height of 381m, the height of the Empire

State Building.

(a) If the coin has a mass of 12g, what is its increase in potential energy? (3)

(b) Assuming all this energy is changed to kinetic energy as it drops, calculate the

speed it would hit the ground at if it fell from rest without spinning. (3)

(c) If the same thing were done with a five pence piece of mass 3.25g what would its

final speed be? Use the same assumption as in (b). (1)

(d) Ignoring air resistance, if the two coins were dropped at the same time from the

same height, how would their falls compare? (1)

(e) Why would neither coin achieve the speed you calculated? (1)



Homework Exercises

(f) If all the potential energy is NOT converted in kinetic energy during the fall

then will it have some potential energy left as it hits the ground?

Explain your answer. (2)

3. {Research Question}

Note well: you may have to visit the school library to

look at books or go online to answer this question.

Machines from Earth have touched many different kinds of object in our Solar

System, for example the planet Mars, the moon Titan, the near-Earth asteroid 433

Eros, and the comet Tempel 1.

(a) Write a sentence or two about one such mission, giving at least one factual detail. (1)

(b) Give a reference to your source of information which another pupil could use to

check your detail practically. You must give enough information that even a pupil

in another school could verify your fact for example by asking their librarian to

order the book. (1)

4. {Open-Ended Question }

From your knowledge of energy, what might a space exploration scientist consider

when sending a machine to land safely on an extra terrestrial body? The machine

must be capable of sending back some intelligible data. (3)

Total 25 marks




Homework Exercises

Homework 10 – Heat Energy

1. (a) What is the difference between a temperature measured in degrees Celsius

and kelvin, the proper (S.I.) unit of temperature? (1)

(b) If a kettle changes the temperature of some water by + 80 ⁰C, what is the

temperature rise in K? (1)

2. Assuming the specific heat capacity of water to be 4200 Jkg-1K-1, how much heat

energy is required to:

(a) Heat 1 kg of water in a kettle from 20°C to 100°C? (3)

(b) Heat 400 litres of water in a tank from 20°C to 60°C?

(1 litre of water has a mass of 1 kg) (3)

3. The block of iron has a mass of 2 kg. The heater is left on for 5 minutes and it

supplies 6000 J of heat energy to the block in this time. The temperature rises

from 20°C to 26.25°C.

(a) What value do these figures give for the specific heat capacity of iron? (3)

(b) Why was the block encased in polystyrene? (1)

4. When a liquid changes to a gas, it takes heat energy in from its surroundings.

(a) What must happen to the temperature of the surroundings? (1)

(b) What happens to the temperature of the liquid as it changes to a gas? (1)

(c) Give an example of an everyday use for this principle. (1)



Homework Exercises

5. Use your knowledge of latent heat to explain why sweating helps to cool your body. (1)

6. A 2 kW kettle contains 1.5 kg of water. Its automatic cut-off is broken, meaning it

will not switch off when it starts to boil. The specific latent heat of vaporisation for

water is 2.26 x 106 Jkg-1.

(a) Calculate how much heat energy would be required to turn all of the water into

water vapour. (3)

(b) How long would the kettle take to evaporate all the water? (3)

7. The specific latent heat of fusion for ice is 3.3 x 105 J/kg. What mass of water

could be turned into ice if a freezer removed 165 000 J of heat energy? (3)

Total 25 marks




Homework Exercises

Homework 11 – Cosmology

1. (a) Use a diagram to show how white light can be split to form a spectrum. (1)

(b) Name a piece of equipment used for this. (1)

(c) What do people mean by ROYGBIV? (1)

2. (a) Use the reference sheet to identify elements A and B (2)

(b) Use the reference sheet to identify the elements present in spectra C, D, E and F. (4)

(c) Which elements are present in all four spectra C, D, E and F? (2)

3. Cosmologists talk about the observable universe. Does that mean that there is an

unobservable region of our universe and if so what can we learn about it? (2)



Homework Exercises

Homework 11 – Cosmology continued

4. (a) Give one piece of experimental evidence that can be used to support the theory

that the universe is expanding. (1) (b) If the universe is expanding, how will its size tomorrow compare with its size today? (1)

.

(c) How will the mass-energy of the entire universe tomorrow compare with today? (1) (d) How will the size and mass-energy of the entire universe 10 billion years in the future

compare with its size and mass-energy today ? (1)

(e) State one of the assumptions that you made in your answer to (d) above. (1)

(f) If the universe is expanding, how did its size yesterday compare with its size today? (1)

(g) How did the mass-energy of the entire universe yesterday compare today? (1)

(h) How did the size and mass-energy of the entire universe 13.8 billion years in the past,

compare with its size and mass-energy today? (1)

(i) State one of the assumptions that you made in your answer to (h) above. (1)

(j) The lump which banged is sometimes called a singularity. Write a sentence or two about

where you think the singularity may have come from or what caused it to expand. (1)

(k) Recent advances in astronomy seem to be showing that the universe is expanding at an

accelerating rate. What is the name given to the theoretical cause of this expansion? (1)

(l) Have cosmologists reached agreement about what is causing this expansion? (1) Total 25 marks (1) Total 25 marks

==== End of Homework 11 ===

PHYSICS - eduBuzz.org · A car's speed is recorded over a period and the results are show in the...

Documents

Transcript of PHYSICS - eduBuzz.org · A car's speed is recorded over a period and the results are show in the...