Post on 17-Jan-2015
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Energy Around Us
Chapter 16
16.1 What is Energy?
Energy is the .
We use energy to .
Without energy,
.
The SI unit for energy is ( ).
ability to do work
live and function
living systems will dieand non-living systems will not function
Joules J
16.2 Forms of Energy
Energy exists in many forms.
Energy in Action Stored Energy
Kinetic EnergyHeat EnergyLight EnergySound EnergyElectrical Energy
Potential EnergyGravitational Potential EnergyElastic Potential Energy
Chemical EnergyNuclear Energy
Kinetic Energy
Kinetic energy is the energy that a body has due to its motion.
Any object that moves has kinetic energy.
Eg. A moving car has kinetic energy
Heat Energy
Heat energy is the energy that flows from a region of higher temperature to a region of lower temperature.
Eg. A hot cup of tea contains heat energy.
Light Energy
Light is the energy that enables us to SEE.
Eg. Light energy is given out by a fire.
Electrical Energy
Electrical energy is a form of energy that involves the flow of electric charges.
Gravitational Potential Energy
Gravitational Potential Energy is the energy an object has because of its position or location.
Any object that is raised from a lower position to higher position gains gravitational potential energy.
Elastic Potential Energy
Elastic Potential Energy is the energy an object has when it is stretched or compressed.
Eg. A stretched rubber band or a compressed spring has elastic potential energy.
Chemical Energy
Chemical energy is the energy stored in fuel (eg. Petrol, Batteries, Food) that can be released through chemical reaction.
Nuclear Energy
Nuclear energy is a form of energy stored in the nuclei of atoms.
Eg. Atomic bombs, nuclear reactor in a nuclear power plant
16.3 Conversion of Energy
Energy can be converted from one form to another.
Examples of Conversion of Energy
Oven Toaster
Electrical Energy Heat Energy
Examples of Conversion of Energy
Television
Electrical Energy Light Energy and Sound
Energy
Examples of Conversion of Energy
Burning Matchstick
Chemical Energy Heat Energy and Light
Energy
Examples of Conversion of Energy
Falling Apple
Gravitational Kinetic Potential Energy Energy
Examples of Conversion of Energy
Atomic Bomb
Nuclear Energy Heat Energy, Light Energy and Sound Energy
Examples of Conversion of Energy
A person shooting a rubber band
Elastic Potential Kinetic Energy Energy
16.4 Principle of Conservation of Energy
Principle of Conservation of energy states that:
Energy cannot be created or destroyed.
It is transferred from one body to another or transformed from one form to another.
Total energy remains constant.
Example: Piling1. The pile hammer is raised to a
height. It gains gravitational potential energy.
2. During the fall, the gravitational potential energy energy is changed to kinetic energy.
3. As the hammer hits the pile, majority of the kinetic energy is transferred to the pile driving the pile into the ground. While some is converted to sound & heat energy.
Example: Swinging of Pendulum
Pendulum bob has its maximum gravitational potential energy and zero kinetic energy at the starting position
Pendulum bob loses all its kinetic energy and gain maximum gravitational potential energy as it comes to rest at its maximum height.
Pendulum bob loses gravitational potential energy and gainskinetic energy as it swings down
Pendulum bob loses all its gravitational potential energy and gain its maximum kinetic energy at the lowest position
Pendulum bob starts to lose its kinetic energyand gain gravitational potential energy as itswings up
Power StationA power station uses fossil fuels such as coal, natural gas and oil.
When these fossil fuels are burnt, the chemical energy stored in these fuels is released to boil water to form steam.
The moving steam turns the generator.
When the generator turns, electrical energy is produced.
Power StationA power station uses fossil fuels such as coal, natural gas and oil.
When these fossil fuels are burnt, the chemical energy stored in these fuels is released to boil water to form steam.
The moving steam turns the generator.
When the generator turns, electrical energy is produced.
Energy Conversion in Power plant
Chemical Energy
Heat Energy
Kinetic Energy
Eletrical Energy
A geothermal power plant uses heat from the
earth.
A hydroelectric power station uses energy from falling water.
A wind turbine uses energy from wind to turn the
turbines.
Different types of Power Station
Conserving Energy
With rapid growth in populations, urbanisation, industrialisation and globalisation, the world is consuming more energy.
There is a need to conserve energy and use it wisely.
Free but expensive sources of energyEnergy from the Sun, wind, rain, tides, nuclear fuels and heat from inside the Earth can be harnessed to do work and improve our quality of life.
These alternative sources of energy are clean and do not run out.
However, they are expensive or unsuitable to harness in some places.
Plants and waste from animals
Fuels such as biogas and alcohol are derived from biomass (plant materials or wastes from living things)
Risky Sources
The production of electrical energy using nuclear fuels is cleaner than that using coal or oil.
However, there is a fear of exposure to harmful radiation should an accident happen in a nuclear power plant.
In Singapore….
Singapore is a small country without natural resources.
Although it is one of the major oil refinery centres of the world, it has to import oil and gas from other countries for production of electrical energy.
There is a need to conserve energy, especially for Singapore.
Caring for Mother Nature
Humans’ need for more and more energy has sparked the global concern that non-renewable energy sources such as fossil fuels will run out one day.
The use of such fuels has heightened environmental concerns regarding air and water pollution as well as global warming.