A motor with an output power of 100 watts is connected to a

A motor with an output power of 100 watts is connected to a flywheel. How long, in units of hours, must the motor operate to transfer 300\'000 joules to the flywheel, assuming the process is 80% efficient?

Solution

1 joule = 1W/sec

SO Energy transferred to the flywheel per second = 100 *80% = 80 joules

TIme required to transfer 300\'000 joules = 300\'000/80 = 3750 seconds (ans) or 62.5 minutes (ans)