Unit 3 - Revision Summary
Power is defined as the rate at which work is done.
Power = Work done¸time
It can also be defined as the rate at which energy is converted from one form into another.
Power is a scalar quantity and its unit is the watt (W).
From the definition it follows that one watt is equivalent to one joule per second;
1 W = 1 J s–1
Power = Force × velocity
Energy = Power × Time
The efficiency of a device, machine or engine is defined as the ratio of power output to power input.
Efficiency (%) = power output / power input x 100
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