Question

a small electric motor is used to raise a weight of 2N through a vertical height of 80cm in 4 seconds. The efficiency of the motor is 20%. What is the electrical power supplied to the. (A) 0.80 W. (B) 2.0 W. (C) 0.080 W. (D) 200W​

Answer 1

Answer:

Option A.

Explanation:

M = 2N

H = 0.8 m

t. = 4 sec

Energy = M x g x H = 2 x 0.8 x 10 = 16 J

Power = Energy/sec = 16/4 = 4 J/s

output at 20% efficiency = 4 x 0.2 = 0.8 W