Question

prove that for two bodies of equal masses when collided with each other then after the collision the two colliding bodies will exchange their velocities

Answer 1

by conservation of linear momentum we know that momentum remains conserved inside a system. so let us consider 2 bodies to be one system
m1u1+m2u2=m1v1+m2v2
as the masses are equal,
u1+u2=v1+v2
hence initail velocity=final velocity
hence proved.