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
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
$7.46 J$
$7400 J$
$ 7.46 ergs$
$74.6 J$
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 =$ $600\frac{{{\rm{revolution}}}}{{{\rm{minute}}}} = 10\frac{{rev}}{{\sec }}$
Time required for one revolution $ = \frac{1}{{10}}$sec
Energy required for one revolution = power $×$ time
=$\frac{1}{4} \times 746 \times \frac{1}{{10}} = \frac{{746}}{{40}}J$
But work done = $40\% $ of input
$ = 40\% \times \frac{{746}}{{40}} = \frac{{40}}{{100}} \times \frac{{746}}{{40}} = 7.46\,J$
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