Question

A small ball of mass m, moving with a velocity v hits a massive smooth wall which is moving towards the
ball with a velocity u (both the velocities are in same line). An-elastic impact takes place between them
for a time interval At.Then
1)The average elastic force acting on the ball due to impact is
m(u + v)
At
2m(u + v)
The average elastic force acting on the ball due to impact is
At
The kinetic energy of the ball increases by 2mu(u + v)
The kinetic energy of the ball remains the same after the collision​

Answer 1

Answer:

The kinetic energy of the ball increases by 2mu(v + u)