Question

A motor hoists a 50-kg crate at constant speed to a height of h=6 m in 3 s. if the indicated power of the motor is 4 kw. Determine the motor's efficiency.

Answer 1

24.52% efficiency

Step-by-step explanation:

Knowns:

Mass = 50 kg

Height = 6 m

Time = 3 s

Indicated Power = 4 kW = 4000 W

Acceleration Due to Gravity = 9.81 m/s^2

Actual Power = Potential Energy / Time = mgh / t

Actual Power = (50 kg * 9.81 m/s^2 * 6 m) / 3 s = 981 W

Motor Efficiency = (Actual Power / Indicated Power) * 100 = (981 W / 4000 W) * 100 = 24.52%