1. The problem statement, all variables and given/known data Two identical balls (same mass and material) , of which the first one (named ball "M") moving in the direction = 3i + 4j collides with the second ball (named ball "S") which is stationary. After the impact, the ball "M" moves in the direction= 3i + 16j while ball "S" moves in the direction = i. Show that this can happen whatever the initial speed of "M" . 2. Relevant equations P(after impact) = P(before impact) (where P denotes the vector quantity momentum) law of restitution. 3. The attempt at a solution U shows Initial velocity let U(of M) be = n( 3i + 4j ) [where n= any "scalar" ,thus showing initial velocity] let U(of S) be = k (oi+0j) = 0 V shows final velocity let V(of M) be = c( 3i + 16j ) [again "c" is a scalar] let V(of S) be = d( i ) [because the impulse and force act horizontally] The velocity in j direction remains constant, while momentum is conserved in the x direction. so i got two equations : 1) 3n = 3c + d [from conservation of momentum in i direction] 2) 4n = 16c ⇔ n/c = 4 [velocity remains unchanged in j direction] I don't know what to do next, how do i prove this ?