Question

An electric motor raises a load of 0.2 kg, at a constant speed, through a vertical distance of 3.0 m in 2 s. If the acceleration of free fall is 10 $m/s^2$, the power in W developed by the motor in raising the load is :

(a) 0.3

(b) 1.2

(c) 3.0

(d) 6.0

Answer 1

(c) 3.0
Power, P = $\frac{W}{t}$
W = mgh = 0.2 $\times$ 10 $\times$ 3 = 6 J

⇒ P = $\frac{6}{2}$
P = 3 watt