Question Detail
Question
In Example 10, what minimum power must the motor deliver to lift the elevator at constant speed?
Correct Answer
Option A is the correct answer.
Detailed Explanation
First, find tension T = f + Mg = 4000 N + (1000+800)kg × 9.8 m/s² = 4000 + 17640 = 21640 N. Then power P = T v = 21640 N × 3 m/s = 64920 W = 64.92 kW, which is approximately 64.8 kW.
Hint
Power = force × velocity when force and velocity are in the same direction.