Two spheres A and B of masses m1 and m2 respectively collide. A is at rest initially and B is moving with velocity v along X-axis. After collision, B has a velocity v/2 in a direction perpendicular to the original direction. The mass A moves after collision in the direction

Initial momentum, pi=m2vi^ + m1×0Final momentum, pf=m2(v/2)j^ + m1×v1From law of conservation of momentum,                             pi=pf                     m2vi^=m2v2j^+m1×v1                          v1=m2m1vi^-m2m1v2j^From this equation, we can find, tanθ=12⇒                      θ = tan-112 to the X-axis.