Let's distinguish between an elastic collision and an inelastic collision.
• Elastic collision:
An elastic collision is a type of collision in which the colliding bodies bounce back after colliding with each other with going through a any deformation.
In this collision, the kinetic energy is not converted to any other form of energy .
In this case both momentum and total energy of both objects are conserved.
• Inelastic collision:
An inelastic collision is a collision where the colliding bodies come to a halt and stick together after collision.
In this collision the energy not conserved while the momentum is conserved.
The kinetic energy turns to heat energy.
