During collision total momentum of all the objects in an isolated system remains constant.

What is constant in a collision?

Although the momentum of individual objects may change during a collision, the total momentum of all the objects in an isolated system remains constant.

Does temperature remain constant in collision?

In collision of two body, the momentum of the body is conserved, but kinetic energy is not conserved, as some part of the energy is wasted in form of friction energy, which increase the surface temperature of the body, thus temperature is also not conserve, hence in a collision of two bodies, the only physical property ...