Question

A 1 kg mass falls from a height of 10 m into a large box filled with sand. What is the speed of the mass just before hitting the box? What is its kinetic energy? The mass travels 2 cm into the sand before coming to rest. What is the average retarding force of sand?

The figure given below shows a smooth curved track terminating in a rough horizontal part. A block of mass 50 g is released from rest from position A at a height of 20 m on the curved track.

While saving a goal (Fig. 7.7b), a goalkeeper's hand moved back by 15 cm as she stopped a ball while applying a force of 200 N. How much work did the goalkeeper do on the ball in stopping it?

A ball of mass 2 kg is thrown up with a velocity of 20 m s–1.