$A$ 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 ........... $m/s^2$ $\left(g=10 \,m/s^2\right)$.

$A$ body is moving along a horizontal surface with a velocity of $4 \,m/s$. If the coefficient of kinetic friction is $0.2$, the distance travelled by the body before coming to rest is $(g = 10 \,m/s^2)$. (in $\,m$)

$A$ block of mass $2 \ kg$ is placed on a rough horizontal surface. If a horizontal force of $20 \ N$ acting on the block produces an acceleration of $7 \ m \ s^{-2}$ in it,then the coefficient of kinetic friction between the block and the surface is $(g = 10 \ m \ s^{-2})$.

$A$ block of mass $m$ rests on a rough horizontal surface as shown in the figure. The coefficient of friction between the block and the surface is $\mu$. $A$ force $F = mg$ acting at an angle $\theta$ with the vertical side of the block pulls it. In which of the following cases can the block be pulled along the surface?

$A$ stationary body of mass $m$ is slowly lowered onto a massive platform of mass $M$ $(M \gg m)$ moving at a speed $V_p = 4 \, m/s$ as shown in the figure. How far will the body slide along the platform (in $, m$)? (Given: $\mu = 0.2$ and $g = 10 \, m/s^2$)

Two blocks $A$ and $B$ of masses $2 \ kg$ and $4 \ kg$ respectively are kept on a rough horizontal surface. If the same force of $20 \ N$ is applied on each block,then the ratio of the accelerations of the blocks $A$ and $B$ is (Coefficient of kinetic friction between the surface and the blocks is $0.3$ and acceleration due to gravity $= 10 \ m \ s^{-2}$).