NCERT Solutions for Chapter: Force And Laws Of Motion, Exercise 2: Short Answer Questions

Two balls of the 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.

Two identical bullets are fired one by a light rifle and another by a heavy rifle with the same force. Which rifle will hurt the shoulder more and why?

A horse continues to apply a force in order to move a cart with a constant speed. Explain why?

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

Velocity versus time graph of a ball of mass $50 \mathrm{g}$ rolling on a concrete floor is shown in figure. Calculate the acceleration and frictional force of the floor on the ball.

A truck of mass $M$ is moved under a force $F$. If the truck is then loaded with an object equal to the mass of the truck and the driving force is halved, then how does the acceleration change?

Two friends on roller-skates are standing $5 \mathrm{m}$ apart facing each other. One of them throws a ball of $2 \mathrm{kg}$ towards the other, who catches it, How will this activity affect the position of the two? Explain your answer.

Water sprinkler used for grass lawns begins to rotate as soon as the water is supplied. Explain the principle on which it works.