The equation used to calculate the power is:
This is when:
One watt is equal to one joule per second (J/s). This means that for every extra joule that is transferred per second, the power increases by one watt.
Two electric motors are used to lift a 2 N weight through a vertical height of 10 m.
Motor one does this in 5 seconds.
Motor two does this in 10 seconds.
For both motors, the energy transferred - the work done - is 20 J.
For motor one:
For motor two:
Since twice as much energy is transferred by motor one each second, it is possible to say that motor one is twice as powerful as motor two.
A hairdryer transfers 48,000 J of energy in one minute. What is the power rating of the hairdryer?