A quarter horse power motor runs at a speed of 600 r.p.m. Assuming 40% efficiency, then what will be the work done by the motor in one rotation?
Power is ¼ hp = 746/4 W = 186.5 W
Since, efficiency of motor is 40%,
The power used in doing work is 40% of 186.5 W, so,
P = 186.5 × 40/100
=> P = 74.6 W
Angular velocity of the motor, ω = 600 rpm = 10 rps
=> ω = (600)(2π)/60 rad/s
=> ω = 20π rad/s
Let the torque be τ.
So, P = τω
=> τ = P/ω = 74.6/(20π)
Work done in 1 rot = (τ)(2π)
=> W = [74.6/(20π)]×(2π)
=> W = 7.46 J