Three blocks are placed as shown in the figure. The masses of $A$,$B$,and $C$ are $m_1$,$m_2$,and $m_3$ respectively. The force exerted by block $C$ on block $B$ is .........

For a particle to be in equilibrium,what must be the net force acting on it?

One end of a horizontal uniform beam of weight $W$ and length $L$ is hinged on a vertical wall at point $O$ and its other end is supported by a light inextensible rope. The other end of the rope is fixed at point $Q$,at a height $L$ above the hinge at point $O$. $A$ block of weight $\alpha W$ is attached at the point $P$ of the beam,as shown in the figure. The rope can sustain a maximum tension of $(2 \sqrt{2}) W$. Which of the following statement$(s)$ is(are) correct?

$A$ book is lying on a table. What is the angle between the normal reaction acting on the book on the table and the weight of the book (in $^\circ$)?

$A$ flexible chain of weight $W$ hangs between two fixed points $A$ and $B$ which are at the same horizontal level. The inclination of the chain with the horizontal at both the points of support is $\theta$. What is the tension of the chain at the mid point?

$P, Q$ and $R$ are three coplanar forces acting at a point and are in equilibrium. Given $P = 1.9318 \, kg \, wt$,$\sin {\theta _1} = 0.9659$,the value of $R$ is (in $kg \, wt$):