Question

State the law of conservation of momentum. Why is a person hit harder when he falls on a hard floor than when he falls on sand from the same height? A bullet of mass 20g is fired horizontally with a velocity 100ms⁻¹ from a pistol of mass 1.5 kg. Calculate the recoil velocity of the pistol.

Rahul and Imran, each weighing 800 N, climb up a rope through a height of 10 meters. Rahul, takes 20 seconds to complete the climb, while Imran, takes 50 seconds. Calculate the power expended by each boy.

Explain the meaning of inertia with the help of an example.

Two balls of same size but of different materials, rubber and iron are kept on the smooth floor of a moving train. The brakes are applied suddenly to stop the train. Will the balls start rolling? If so, in which direction? Will they move with the same speed? Give reasons for your answer.

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