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 \( = 40\% \times \frac{{746}}{{40}} = \frac{{40}}{{100}} \times \frac{{746}}{{40}} = 7.46\,J\)