A thin uniform square plate with side l and mass M can rotate freely abouta stationary vertical axis coinciding with one of its sides . A small ball of mass m flying with velocity v at right angles to the plate strikes elastically to the centre of it. Find the velocity of the ball v'after the impact and the horizontal component of the force which the axis will exert on the plate after the impact.
`[(3m-4M)/(3m+ 4M)v , (72Mm^(2)v^(2))/(l(3m+ 4m)^(2))]`