The energy transferred in this picture is…….

Learning objectives Describe the energy transfers in a range of devices. Identify where energy is wasted. Explain why wasted energy is difficult to use.

Forms of energy click

Forms of energy Energy is needed to keep us working, and to operate all the machines around us. Different forms of energy include….. Light, sound, electrical, potential and kinetic energy. Energy can also be stored. Nuclear energy is stored inside atoms. Food, fuels and electric batteries are stores of Chemical energy. Anything that is squashed, stretched or twisted stores Elastic potential energy. An object in a high position stores energy as Gravitational potential energy.

Energy transfers Machines transfer energy between different forms. An mp3 player transfers stored chemical energy into electrical energy and sound energy. Sometimes more than one transfer is involved. The engine of a car transfers chemical energy in the petrol into kinetic energy (useful) and heat and sound (not useful and called wasted energy).

Click (select no option)

Q) Label the useful and the wasted energy

Conservation of energy Energy cannot be created or destroyed, it can only be transferred usefully, stored or wasted (called dissipated). THE TOTAL AMOUNT OF ENERGY DOES NOT CHANGE. This is called the principle of conservation of energy.

Spreading out If you look at an energy transfer it can often seem as if some of the energy has ‘disappeared’. For example, a car uses chemical energy stored in its fuel. The fuel stores a lot of energy in a small space. This chemical energy is eventually transferred by heating into the surroundings, which become warmer. This dissipated energy is very difficult to use for further energy transfers.

Questions  What are the energy transfers of a torch?  You are running in sports day. What forms of energy are you transferring that are A) useful and B) wasted?  A car uses a litre of petrol when it is driven to the shops and back. What happens to the chemical energy that was stored in the petrol?

 What are the forms of energy produced in a Bunsen burner?  If energy cannot be destroyed, how can we ‘waste’ energy?  Draw a flow chart to show all the energy transfers in a wind-up torch, starting with food. Show how energy is wasted at each stage.