A motor of input power 160 W raises a mass of 8.0 kg vertically at a constant speed of 0.50 m s.What is the efficiency of the system?A. 0.63%B. 25%C. 50%D. 100%
Question
A motor of input power 160 W raises a mass of 8.0 kg vertically at a constant speed of 0.50 m s.What is the efficiency of the system?A. 0.63%B. 25%C. 50%D. 100%
Solution
To solve this problem, we first need to calculate the work done by the motor. The work done (W) is given by the formula:
W = m * g * h
where: m = mass = 8.0 kg g = acceleration due to gravity = 9.8 m/s^2 h = height = speed * time = 0.50 m/s * 1 s = 0.50 m
Substituting the values, we get:
W = 8.0 kg * 9.8 m/s^2 * 0.50 m = 39.2 J
This is the output power. The input power is given as 160 W.
The efficiency (E) of the system is given by the formula:
E = (Output power / Input power) * 100%
Substituting the values, we get:
E = (39.2 J / 160 W) * 100% = 24.5%
So, the closest answer is B. 25%.
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