Laws of Motion

Assertion : A rocket moves forward by pushing the surrounding air backwards. Reason : It derives the necessary thrust to move forward according to Newton's third la

Assertion : Frictional forces are conservative forces. Reason : Potential energy can be associated with frictional forces.

Assertion : A cloth covers a table. Some dishes are kept on it. The cloth can be pulled out without dislodging the dishes from the table. Reason : For every action there is an equal and opposite reaction.

Assertion : When a cyclist doubles his speed of turning, the chance of his skidding becomes nearly four times. Reason: When the speed of the vehicle increases, the angle of bending also increases.

Assertion : Sometimes insects can walk on water. Reason : The gravitational force on insect is balanced by force due to surface tension.

A cart has mass 2 metric tone and sand of 1 metric tone is inside the cart. Now a force of $10 \mathrm{~N}$ is applied on cart and sand starts to leak with rate of $0.5 \mathrm{~kg} / \mathrm{s}$. What is the velocity…

Assertion: On a banked curved track, vertical component of normal reaction provides the necessary centripetal force. Reason : Centripetal force is not always required for turning.

The rear side of a truck is open and a box of mass $20 \mathrm{~kg}$ is placed on the truck $4 \mathrm{~m}$ away from the open end. If $\mu$ is 0.15 and $g$ is $10 \mathrm{~m} \mathrm{~s}^{-2}$ and the truck starts from…

In the diagram $100 \mathrm{~kg}$ block is hanging from a pulley and force $F$ is applied on the string to keep the system in equilibrium. If the whole system is moving up with a constant velocity $v$, then tension at…

Assertion : Two bodies of masses $M$ and $m$ $(M>m)$ are allowed to fall from the same height if the air resistance for each be the same then both the bodies will reach the earth simultaneously. Reason : For same air…

Assertion : Pseudo force is an imaginary force which is recognised only by a non-inertial observer to explain the physical situation according to Newton's laws. Reason : Pseudo force has no physical origin, i.e., it is…

The figure shows a horizontal force $\vec{F}$ acting on a block of mass $\mathrm{M}$ on an inclined plane (angle $\theta$). What is the normal reaction $N$ on the block?