International GCSE (9-1): Physics, for Edexcel International GCSE, Second Edition by Nick England

Author:Nick England [England, Nick]
Language: eng
Format: epub
Publisher: Hodder Education
Published: 2017-04-07T04:00:00+00:00

Power

Often when we want to do a job of work, we want to do it quickly. A crane that lifts a crate more quickly than another crane lifting the same crate is more powerful.

Power is defined as the rate at which energy is transferred or the rate at which work is done. Power can be calculated by using these equations.

An energy transfer of 1 joule per second is equal to a power of 1 watt.

Large powers are also measured in kilowatts, kW, and megawatts, MW.

1 kW = 1 000 W (103 W) 1 MW = 1 00 000 W (106 W)

Example. A weight lifter lifts a mass of 140 kg a height of 1.2 m in 0.6 s. Calculate the power developed by the weight lifter.

The potential energy transferred = mgh

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