P3 â€“ What a waste?

(Energy efficiency)

1) Fill in the gaps for the following energy transfers: a) A torch transfers ___________ to light energy. b) A model steam engine transfers chemical energy to ____________ energy, via thermal energy. c) A pendulum transfers ____________________ energy into kinetic (movement) energy. d) A ball on a slope transfers ____________________ energy into kinetic (movement) energy. e) A hairdryer transfers ____________________ energy into heat energy. f) A wind-up radio transfers ____________________ energy into sound energy. g) A Motor transfers ___________________energy into ______________energy. H) A drill transfers ___________________energy into ______________energy. The % efficiency of an energy transfer can be calculated by: USEFUL Energy OUT x100 Energy in The efficiency of An energy transfer can be calculated by: USEFUL Energy OUT Energy in

2)Calculate the efficiency of a light bulb that gives of 40J of light from 200J of electrical energy.

3) Calculate the percentage efficiency of a motor that does of 60J of work from 240J of electrical energy.

4) Calculate the efficiency of a radio that gives of 30J of sound from 300J of electrical energy.

5)Calculate the efficiency of a runner who produces of 500J of kinetic energy from 2500J of chemical energy. 6) Calculate the percentage efficiency of a kettle that gives 50J of heat from 1000J electricity.

7)

This Sankey diagram shows how much energy is usefully transferred by the kettle. Use the information provide to calculate % efficiency of the kettle. Energy in 1000J

Useful energy

Waste energy

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