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Work done, power and efficiency

Energy · Lesson 2 of 5

Lesson 2 of 5

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Lesson 2 of 5 · Energy

Work done, power and efficiency

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By the end you’ll be able to

calculate work done by a force using $W = Fs$ when a force causes a displacement in the direction of the force
explain that doing work transfers energy and apply this to mechanical, electrical and thermal contexts
calculate power as the rate of energy transfer or the rate of doing work using $P = \frac{E}{t}$ and $P = \frac{W}{t}$

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calculate efficiency as $\text{efficiency} = \frac{\text{useful energy output}}{\text{total energy input}}$ or $\frac{\text{useful power output}}{\text{total power input}}$, and convert between decimal and percentage forms

explain why efficiency is always less than or equal to 1 or 100\% and evaluate methods used to reduce unwanted energy transfers

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