Give an example of the of conservation of momentum

Refraction is the bending of a wave when it enters a medium where its speed is different. This phenomenon is explained by the conservation of energy and conservation of momentum.

Law of Conservation of energy states the total energy of an isolated system remains constant.

law of conservation of momentum states that in a closed system the total momentum is constant.

In refraction, when a medium changes, the phase velocity also changes but its frequency does not; it remains constant.