$A$ uniform cylinder rests on a cart as shown. The coefficient of static friction between the cylinder and the cart is $0.5$. If the cylinder is $4\, cm$ in diameter and $10\, cm$ in height,which of the following is the minimum acceleration of the cart needed to cause the cylinder to tip over? (Assume $g = 10\, m/s^2$)

Two blocks,$4\, kg$ and $2\, kg$,are sliding down an inclined plane as shown in the figure. The acceleration of the $2\, kg$ block is ........ $m/s^2$.

In the figure shown,all surfaces are frictionless,and the mass of the block is $m = 1\, kg$. The block and wedge are held initially at rest. Now,the wedge is given a horizontal acceleration of $a = 10\, m/s^2$ by applying a force on the wedge,such that the block does not slip on the wedge. Calculate the work done by the normal force in the ground frame on the block in $\sqrt{3}$ seconds. (Assume $\tan \theta = a/g = 1$,so $\theta = 45^\circ$)

In the arrangement shown in the figure,if the blocks of masses $m$ and $2m$ are released from rest,find the tension in the string. (Given: $\mu_1 = 2/3$ for mass $m$,$\mu_2 = 1/3$ for mass $2m$,the string is massless and inextensible,and the pulley is frictionless.)

$A$ man balances himself in a horizontal position by pushing his hands and feet against two parallel walls. His centre of mass lies midway between the walls. The coefficients of friction at the walls are equal. Which of the following is not correct?

Work done by a frictional force is