Two spheres of equal mass collide, with the collision being absolutely elastic but not central. Prove that in this case the angle between the velocities after collision must be `90^@`.

Prove that bodies of identical masses exchange their velocities after head-on elastic collision.

Two balls of equal masses m each undergo oblique collision. If colision is perfectly elastic, then angle between their velocities after collision is

A sphere of mass m_1 moving with a velocity v_o hits a sphere of mass m_2 that is at rest. The collision is absolutely elastic "and central. The velocities of the spheres after collision are u_1 and u_2 , respectively. What are the mass ratios for the following values of velocities: u_1=0, u_1 lt 0, and u_1 gt 0 ?

A ball of mass m moving with a velocity v undergoes an oblique elastic collision with another ball of the same mass m but at rest. After the collision if the two balls move with the same speeds , the angle between their directions of motion will be: