The energy transferred in this picture is Learning

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 mp 3 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 o o o 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?

o o o 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 energy is wasted at each stage.