A block of mass $70\,kg$ is kept on a rough horizontal surface $(\mu = 0.4)$. A person is trying to pull the block by applying a horizontal force, but the block is not moving. The net contact force exerted by the surface on the block is $F$, then

A chain of length $L$ rests on a rough table. If $\mu $ be the coefficient of friction, the maximum friction of the chain that can hang over the table will be

A car is moving along a straight horizontal road with a speed ${v_0}$. If the coefficient of friction between the tyres and the road is $\mu $, the shortest distance in which the car can be stopped is

Given in the figure are two blocks $A$ and $B$ of weight $20\, N$ and $100\, N$, respectively. These are being pressed against a wall by a force $F$ such that the system does not slide as shown. If the coefficient of friction between the blocks is $0.1$ and between block $B$ and the wall is $0.15$, the frictional force applied by the wall on block $B$ is ........ $N$

Two blocks $A$ and $B$ are released from the top of a rough inclined plane so that $A$ slides along the plane and $B$ falls down freely. Which will have higher velocity on reaching the ground ?

A block of mass $4\,kg$ is placed on a rough horizontal plane A time dependent force $F = kt^2$ acts on the block, where $k = 2\,N/s^2$. Coefficient of friction $\mu = 0.8$. Force of friction between block and the plane at $t = 2\,s$ is ....... $N$