A propeller is spun up from rest to 1500 rpm in 15.0 s under the influence of a constant torque. If the work done by the engine in giving the propeller its final angular velocity is 25 kJ, what is the torque supplied by the engine?
A) 21 N·m
B) 11 N·m
C) 42 N·m
D) 3.4 N·m
E) 130 N·m

Question

Quizplus · Accepted Answer

The work done by the engine is equal to the torque multiplied by the angular displacement. First, convert 1500 rpm to rad/s, then use the work-energy principle: Work = Torque × Angular Displacement. Angular displacement can be found using the average angular velocity and time. Solving for torque gives approximately 21 N·m.

A Propeller Is Spun Up from Rest to 1500 Rpm