Question

A body of mass 3 kg starts from rest with a uniform acceleration of unknown magnitude. If the body has a velocity of 30 m/s in 6 seconds, what is the power consumed in 3 seconds?

(a) 125 W

(b) 225 W

(c) 325 W

(d) 425 W

I had been asked this question in unit test.

Query is from Power topic in section Work, Energy and Power of Physics – Class 11

Answer 1

Right option is (b) 225 W

Easy explanation: v = u + at

30 = a x 6

a = 5 m/s^2

Force (F) = m x a

 = 3 x 5

 = 15 N

v’ = u + at’

v’ = 5 x 3

 = 15 m/s

Power consumed in 3 seconds = F x v’

 = 15 X 15

 = 225 W.