Block $A$ of mass $4 \mathrm{kg}$ and block $B$ of mass $6 \mathrm{kg}$ are resting on a horizontal surface as shown in the figure. There is no friction between the block $B$ and the horizontal surface. The coefficient of friction between the blocks is $0.2$. If the value of $g=10{ \mathrm{m} \mathrm{s}}^{-2}$, the maximum horizontal force $F$ that can be applied on the block $B$ without any relative motion between $A$ and $B$ is

Consider the situation shown in the figure. The wall is smooth but the surface of $A$ and $B$ in contact are rough. The friction on $B$ due to $A$ in equilibrium

The system shown in the figure is in equilibrium. The maximum value of $W$, so that the maximum value of static frictional force on a body is $450 \mathrm{N}$, will be

A block of mass $20 \mathrm{kg}$ is kept on a rough incline plane. If the angle of repose is $30°$, then what should be the value of $F_{\mathrm{ext}}$, so that the block does not move over the inclined plane?

The coefficient of static friction, ${\mu }_3$ between the block $A$ of mass $2 \mathrm{kg}$ and the table as shown in the figure is $0.2$. What would be the maximum mass value of the block $B$, so that the two blocks do not move? The string and the pulley are assumed to be smooth and massless $\left(g=10 \mathrm{m} {\mathrm{s}}^{-2}\right)$