Question

Two friends on roller-skates are standing 5 m apart facing each other. One of them throws a ball of mass 2 kg towards the other, who catches it, How will this activity affect the position of the two? Explain your answer.

Answer 1

Due to this activity, the separation between them will increase. Initially, the momentum of both is zero as they are at rest. In order the conserve the momentum, the one who throws the ball would move backward and the second one will experience a net force after catching the ball and, therefore, will move backward, that is, in the direction of the force.