Question

Suppose a ball of mass m is thrown vertically upward with an initial speed, its speed decreases continuously till becomes zero. Therefore the ball begins to fall downward and attains the speed again before striking to the ground. It impulses that magnitude of initial and final momenta of the ball are same. Yet it is not an example of conservation of the momentum. Explain why.

Answer 1

Momentum of a system remains conserved if no external force acts on the system. In the given example, there is gravitational force acting on the ball which is an external force, so it is not an example of conservation of momentum.

Answer 2

Momentum of a system remains conserved if no external force acts on the system. In the given example, there is gravitational force acting on the ball which is an external force, so it is not an example of conservation of momentum