The velocity of two objects after collision ()can be calculated from velocity before collisions () and mass of two objects ().

From conservation of momentum

,

and conservation of energy

So

and , which means

So

i.e. The equation need to be solved are

and

The result is

and

where

It means that and

or and where ...etc.

From the point of center of mass coordinate system: both particles bounce back with the same speed (relative to center of mass).