Question

A quarter horse power motor runs at a speed of $600\, rpm$. Assuming $40\%$ efficiency the work done by the motor in one rotation will be

• A. 7.46 J
• B. 7400 J
• C. 7.46 erg
• D. 74.6 J

Answer 1

Answer: (A)

7.46 J

Answer 2

$P \times 40 \%=\frac{W}{t}$ $\Rightarrow \frac{746}{4} \times \frac{40}{100}=\left(\frac{w}{2 \pi \times \frac{600 \times 2 \pi}{60}}\right)$ $\therefore W=7.46\, J$