Block $A$ of mass $4 \mathrm{kg}$ is to be kept at rest against a smooth vertical wall by applying a force $F$ as shown in figure. The force required is $\left(g=10 \mathrm{m} {\mathrm{s}}^{-2}\right)$

A block of mass $m$ as shown in figure is pulled by a force $40 N.$ The tension at the middle of the block is

In the given arrangement, the normal force applied by block on the ground is

Three blocks are placed as shown in figure. Mass of $A, B$ and $C$ are $m_1, m_2$ and $m_3$ respectively. The force exerted by block$\text{'}C\text{'}$ on $\text{'}B\text{'}$ is

The value of $\frac{T_3}{T_1}$ is

A block of mass $10 \mathrm{kg}$ is moving on a rough surface as shown in figure. The frictional force acting on block is

Block of mass $10 \mathrm{kg}$ is moving on inclined plane with constant velocity $10 \mathrm{m} {\mathrm{s}}^{-1}.$ The coefficient of kinetic friction between incline plane and block is