$A$ child weighing $25 \,kg$ slides down a rope hanging from a branch of a tall tree. If the force of friction acting against him is $200 \,N$,the acceleration of the child is ........... $m/s^2$ $\left(g=10 \,m/s^2\right)$.

$A$ block of mass $40 \,kg$ slides over a surface,when a mass of $4 \,kg$ is suspended through an inextensible massless string passing over a frictionless pulley as shown below. The coefficient of kinetic friction between the surface and the block is $0.02$. The acceleration of the block is ............ $m/s^2$. (Given $g = 10 \,m/s^2$.)

$A$ cylinder of mass $12 \,kg$ is sliding on a plane with an initial velocity $20 \,ms^{-1}$. If the coefficient of friction between the surface and the cylinder is $0.5$, what is the distance the cylinder travels before stopping (in $\,m$)?

Consider a car moving on a straight road with a speed of $100\, m/s$. The distance at which the car can be stopped is ........ $m$. $[\mu_k = 0.5, g = 10\, m/s^2]$

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 ........ $N$.

$A$ conveyor belt is moving at a constant speed of $2\, ms^{-1}$. $A$ box is gently dropped on it. The coefficient of friction between them is $\mu = 0.5$. The distance that the box will move relative to the belt before coming to rest on it,(taking $g = 10\, ms^{-2}$) is ........ $m$.