A quarter horse power motor runs at a speed of 600 r.p.m. Assuming 40% efficiency the work done by the motor in one rotation will be

Motor makes 600 revolution per minute∴n=600revolutionminute=10revsec∴Time required for one revolution =110secEnergy required for one revolution = power × time                         = 14×746×110=74640JBut work done = 40% of input                          =40%×74640=40100×74640=7.46 J