Answer:

1. Both objects have experienced the same change in momentum,since both fall from the same height, their velocity near the ground is equal.

2.The collision of the ball that falls on a hard ground cause a greater impact on both the ball and the ground.On the other hand, the collision with the sponge does not cause any harm in any of the objects in contact as it is absorbed by sponge's softness.

3.Hence,the collision is slower and more extended in time compared to the first case due to the elastic properties of sponge.