Question

How much work is needed to be done on a ball of mass 50 g to give it a momentum of 5 kg m $s^{-1}$?

Answer 1

Mass of the ball, m = 50 g = 0.05 kg

Initial velocity, u = 0

Final momentum = 5 kg m/s

Final velocity, $v=\frac{Finalmomentum}{Mass}=\frac{5}{0.05}=100m/s$

So, work done = Change in KE of the ball $=\frac{1}{2}m{v}^2=\frac{1}{2}\times 0.05\times {100}^2=250J$