V K Sally and R Goel Solutions for Chapter: Force and Laws of Motion, Exercise 12: EXERCISE

Why does a boatman ties his boat to a pillar, before allowing the passengers to step on the river bank? Explain.

Why does a gun recoil backward when fired? Explain.

Why is it easier to stop a tennis ball than a cricket ball, moving at the same speed? Explain.

Why are the road accidents at higher speeds more disastrous, as compared to those at low speeds? Explain.

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?

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

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.