A body 'x' with a momentum 'p' collides with another identical stationary body 'y' one dimensionally. During the collision 'y' gives an impulse 'J' to the body 'x'. Then the coefficient of restitution is
Initial momentum of body - 1 = p. As the impulse transeferred by y to x is in a direction opposite to the direction of initial motion of x, its final momentum mv2 = p + (-J). Also, since impulse transferred by x to y is in the direction of motion of y , we can write, mv2 = J