AQA P1.2 Energy and efficiency

What does energy conservation mean?

Energy can be transferred usefully, stored, or dissipated, but cannot be created or destroyed.

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What are the 9 types of energy?

Kinetic (movement), heat, light, gravitational potential (being high up), chemical (released in chemical reactions e.g. burning), sound, elastic potential (stretch or squashing), electrical (carried by charged particles), nuclear (stored in nuclei)

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How can you remember the 9 types of energy?

Use the mnemonic 'Kids Hate Learning G C S E Energy Names'

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Which energies are usually wasted and why?

Heat and sound. Wasted energy is eventually transferred to the surroundings, which become warmer. The wasted energy becomes increasingly spread out and so becomes less useful.

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What is energy measured in?

Joules (J)

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What is efficiency?

How much USEFUL energy comes out of a device compared to how much you put into it (the equations are on the formula sheet)

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What is payback time?

How long you would need to own and run a more efficiency appliance for to make back the money you spent on it in savings on your electricity/gas bill

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What is the formula for payback time (memorize this - not given)?

Payback time = cost of appliance ÷ savings per day/month/year. NOTE: the unit for payback time is whatever your 'savings per....' is in. IF YOU ARE GIVEN THIS DATA YOU MUST CALCULATE PAYBACK TIME TO GET THE MARKS

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What is a sankey diagram?

A diagram, drawn to scale, that shown the energy input to a device and the useful and wasted energy outputs as arrows. NOTE: IT IS THE THICKNESS OF THE ARROWS THAT TELL YOU HOW MUCH ENERGY THERE IS, NOT THE LENGTH

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How do you draw a sankey diagram?

(1) choose a scale e.g. 1 square represents 10J of energy. Draw the input energy on the left as the base of the sideways arrow. (2) Draw the useful energy pointing sideways and wasted energy pointing up or down off the main arrow. (continued)

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sankey continued

(4) label how much energy is wasted, useful and input. (5) label the names of the wasted, useful and input energies. REMEMBER SANKEY DIAGRAMS ARE DRAWN TO SCALE - THE THICKNESS OF EACH ARROW REPRESENTS HOW MUCH ENERGY THERE IS

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If comparing the use of different appliances, what can you comment on?

How much it costs to install and run. How much money is saved by using it (and therefore calculate payback time), low payback time= cost effective. but it won't be cost effective if it's payback time is longer than it's lifespan

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What are the advantages of buying new appliances?

Uses less energy so reduces emissions into atmosphere • lower input power or uses less energy or wastes less energy • usually costs less to run

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What are the disadvantages of buying new appliances?

• old ones go to land fill • energy waste in production • cost or difficulty of disposal, usually more expensive to buy • transport costs

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AQA P1.2 Energy and efficiency

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