The blocks shown in the figure move with a constant velocity of $10 \, m/s$ towards the right. All surfaces in contact are rough. The friction force applied by the ground on block $B$ is ........ $N$.

$A$ car is moving along a straight horizontal road with a speed $v_0$. If the coefficient of friction between the tyres and the road is $\mu$,the shortest distance in which the car can be stopped is

$A$ block of mass $M = 5\,kg$ is resting on a rough horizontal surface for which the coefficient of friction is $0.2$. When a force $F = 40\,N$ is applied at an angle of $30^\circ$ with the horizontal,the acceleration of the block will be ........ $m/s^2$ $(g = 10\,m/s^2)$.

$A$ body is travelling with $10 \,ms^{-1}$ on a rough horizontal surface. Its velocity after $2 \,s$ is $4 \,ms^{-1}$. The coefficient of kinetic friction between the block and the plane is (acceleration due to gravity $= 10 \,ms^{-2}$)

Why are rubber tires preferred over steel tires for vehicle wheels?

The power required for an engine to maintain a constant speed of $50 \,m \,s^{-1}$ for a train of mass $3 \times 10^6 \,kg$ on rough rails is (The coefficient of kinetic friction between the rails and wheels of the train is $0.05$ and acceleration due to gravity $= 10 \,m \,s^{-2}$).