A box of mass $m\, kg$ is placed on the rear side of an open truck accelerating at $4\, m/s^2$. The coefficient of friction between the box and the surface below it is $0.4$. The net acceleration of the box with respect to the truck is zero. The value of $m$ is :- $[g = 10\,m/s^2]$

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 ....... $N$

A heavy uniform chain lies on a horizontal table-top. If the coefficient of friction between the chain and table surface is $0.25$, then the maximum fraction of length of the chain, that can hang over one edge of the table is ...... $\%$

A block of mass $5\, kg$ is $(i)$ pushed in case $(A)$ and $(ii)$ pulled in case $(B)$, by a force $F = 20\, N$, making an angle of $30^o$ with the horizontal, as shown in the figures. The coefficient of friction between the block and floor is $\mu = 0.2$. The difference between the accelerations of the block, in case $(B)$ and case $(A)$ will be ........ $ms^{-2}$ .$(g = 10\, ms^{-2})$

For the given figure, if block remains in equilibrium position then find frictional force between block and wall ........ $N$ 

For the given figure, if block remains in equilibrium position then find frictional force between block and wall ........ $N$