Machine-translated by Google. Questions are authored in English.
Top

Discussion

A dc motor developing 60 N·m at 1,200 rpm delivers a shaft power of nearest

  • A.72 kW
  • B.0.05 kW
  • C.1.2 kW
  • D.7.5 kW

Answer: D

Correct answer: 7.5 kW

Shaft power is torque times angular velocity:

\[ P = T\omega = 60 \times \frac{2\pi \times 1200}{60} = 60 \times 125.7 \approx 7540 \text{ W} \approx 7.5 \text{ kW} \]

The speed must be converted from revolutions per minute to radians per second before multiplying - the 72 kW answer comes from using 1200 directly, and the 1.2 kW answer from mishandling the same conversion the other way.

No comment is present. Be the first to comment.
Loading…

Post your comment

Please log in or register to post a comment.