Define power. A boy of mass 45 kg climbs up 20 steps in 20 sec. If each step is 25 cm high, calculate the power of the boy used in climbing. (Take g = 10 m s^-2)

[prasanna]

Power is defined as the rate of doing work.
Now, m = 45 kg,
n = 20,
t = 20 s,
h = 0.25 x 20 = 5 m
P = W / t = mgh / t
= (45 x 10 x 5)/20
= 112.5 W