A) 7.46 J
B) 7400 J
C) 7.46 erg
D) 74.6 J
Correct Answer: D
Solution :
Motor makes 600 rotation per minute \[\therefore \] \[n=600\frac{rotation}{\min ute}=10\frac{rev}{\sec }\] \[\therefore \]Time required for one rotation \[=\frac{1}{10}s\] Energy required for one rotation = power\[\times \]time \[=\frac{1}{4}\times 746\times \frac{1}{10}\] \[=\frac{746}{40}J\] But work done = 40% of input \[=40%\times \frac{746}{40}=0.40\times \frac{746}{40}\] \[=7.46J\]
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