Question

A wheel rotates with an angular velocity of 420 revolutions/minute when power of 660 W is transferred to it. The torque acting on the wheel is:

• A. 25 N m
• B. 18.5 N m
• C. 15 N m
• D. 12.5 N m

Hint:

Power in rotational motion is related to torque and angular velocity: \(P = \tau \omega\). Always convert rev/min to rad/s.

Answer 1

The Correct Option is C

Step 1: Converting angular speed.
ω = 420 rev/min = 420 × (2π/60) ≈ 44 rad/s.

Step 2: Power-torque relationship.
P = τ ω → τ = P/ω = 660/44 ≈ 15 N m.

Step 3: Conclusion.
The torque acting is 15 N m.