Sunil Batra Solutions for Chapter: Force and Laws of Motion, Exercise 4: HOTS Higher Order Thinking Skill & Brain Twisting

Two persons manage to push a motorcar of mass $1200 \mathrm{kg}$ at a uniform velocity along a level road. The same motorcar can be pushed by three persons to produce an acceleration of $0.2 \mathrm{m} {\mathrm{s}}^{-2}$. With what force does each person push the motorcar? (Assume that all persons push the motorcar with the same muscular effort.)

A hammer of mass $500 \mathrm{g}$, moving at $50 \mathrm{m} {\mathrm{s}}^{-1}$, strikes a nail. The nail stops the hammer in a very short time of $0.01 \mathrm{s}$. What is the force of the nail on the hammer?

A motor car of mass $1200 \mathrm{kg}$ is moving along a straight line with a uniform velocity of $90 \mathrm{km} {\mathrm{h}}^{-1}$. Its velocity is slowed down to $36 \mathrm{km} {\mathrm{h}}^{-1}$ in $4$ seconds by an unbalanced force. Calculate the acceleration and change in momentum. Also calculate the magnitude of force required.

Air is blown on a sail attached to a boat from an electric fan which is placed on the boat. Will the boat start moving?

Can a rocket propel itself in vacuum. Explain.

What type of force is acting on the body whose motion is shown in the following $\mathrm{v}-\mathrm{t}$ graph.

Velocity-time graph

What type of force is acting on the body whose motion is shown in the following $\mathrm{v}-\mathrm{t}$ graph.

Velocity-time graph

What type of force is acting on the body whose motion is shown in the following $\mathrm{v}-\mathrm{t}$ graph.

Velocity-time graph