  When a cyclist brakes thermal (heat) energy is produced by friction.

# Energy Transfers 01

## Revise what you know about kinetic energy. Where would you find some chemical energy?

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This KS3 Science quiz takes a look at energy transfers. The Law of Conservation of Energy states that energy can be transferred from one type to another, it can't be created or destroyed. This is actually quite useful as it means that we can make things happen. An example of this is getting to school by bus. The bus has a tank of fuel (e.g. diesel). This is a store of chemical energy. The engine of the bus transfers the chemical energy into heat energy by burning it. This heat energy is then converted into kinetic energy as the burning fuel causes the pistons to move up and down. The kinetic energy is used to turn the bus wheels. We would say that the MAIN energy change for the bus is chemical energy to kinetic energy because that is the form of energy that we want.

No energy change is one hundred percent efficient. In the case of the bus, some of the heat energy heats up the engine and does not help to move the pistons.

It is wasted. Some of the heat energy is lost through the exhaust pipe - more is wasted. Still more of the kinetic energy is wasted as heat because of friction between moving parts. In fact, only about a third of the stored chemical energy becomes kinetic energy. The most common wasted energy is heat. This spreads out into the environment and cannot be used anymore.

1.
Which is the MAIN energy transfer taking place when a gas fire burns?
Chemical → sound
Chemical → thermal
Thermal → chemical
Thermal → light
The energy stored in gas is chemical, light is also produced but is not the main product
2.
Which is the MAIN energy transfer in a solar cell on a calculator?
Electrial → light
Light → electrical
Light → kinetic
Light → thermal
Solar cells can be used on a much larger scale to generate electricity
3.
Which is the MAIN energy transfer taking place when a candle burns?
Chemical → light
Chemical → sound
Light → chemical
Thermal → chemical
Thermal (heat) energy is also produced
4.
Which is the MAIN energy transfer in a loudspeaker?
Electrical → sound
Electrical → thermal
Sound → electrical
Sound → thermal
The electrical signals vibrate a cone in the loudspeaker to produce sound waves
5.
Which is the MAIN energy transfer when a light bulb is switched on?
Electrical → light
Electrical → sound
Light → electrical
Light → thermal
Heat energy is also produced but that is wasted
6.
Which is the MAIN energy transfer when a ball rolls UP a ramp?
Kinetic → potential
Kinetic → thermal
Potential → kinetic
Potential → sound
As the ball rolls upwards, it gains potential energy but the movement gradually slows down as the kinetic energy is transferred
7.
Which is the MAIN energy transfer when a cyclist brakes to stop?
Kinetic → elastic
Kinetic → potential
Kinetic → thermal
Thermal → kinetic
The thermal (heat) energy is produced by friction
8.
Which is the MAIN energy transfer when you drop a ball?
Kinetic → potential
Kinetic → sound
Potential → kinetic
Potential → thermal
The ball has potential (stored) energy due to gravity
9.
Which is the MAIN energy transfer when using a microphone?
Electrical → sound
Electrical → thermal
Sound → electrical
Sound → thermal
A microphone converts sound into an electrical signal. This can then be saved to a computer file or amplified and sent through a loudspeaker system so that it can be heard further away
10.
Which is the MAIN energy transfer when a wind-up clockwork toy is released?
Elastic → kinetic
Elastic → potential
Kinetic → elastic
Kinetic → sound
The spring unwinds because of the stored elastic potential energy it contains. As the spring does this, its movement can be used to make the toy do things 