$A$ horizontal force $F = mg/3$ is applied on the upper surface of a uniform cube of mass $m$ and side $a$,which is resting on a rough horizontal surface having $\mu_S = 1/2$. The distance between the lines of action of $mg$ and the normal reaction $N$ is:

$A$ cubical box of side $a$ sitting on a rough table-top is pushed horizontally with a gradually increasing force until the box moves. If the force is applied at a height from the table top which is greater than a critical height $H$,the box topples first. If it is applied at a height less than $H$,the box starts sliding first. Then,the coefficient of friction between the box and the table top is

The figure shows a man standing stationary with respect to a horizontal conveyor belt that is accelerating with $1 \; m/s^2$. What is the net force on the man? If the coefficient of static friction between the man's shoes and the belt is $0.2$,up to what acceleration of the belt can the man continue to be stationary relative to the belt? (Mass of the man $= 65 \; kg.)$

What is the acceleration of the block and trolley system shown in the figure,if the coefficient of kinetic friction between the trolley and the surface is $0.04$? What is the tension in the string? (Take $g = 10\; m s^{-2}$). Neglect the mass of the string.

$A$ constant force $F$ is applied in the horizontal direction as shown. If the contact force between $M$ and $m$ is $N$ and the contact force between $m$ and $M'$ is $N'$,then:

In the figure,a block of weight $60 \ N$ is placed on a rough surface. The coefficient of friction between the block and the surface is $0.5$. What should be the maximum weight $W$ (in $N$) such that the block does not slip on the surface?