$A$ boy of mass $40 \,kg$ is climbing a vertical pole at a constant speed. If the coefficient of friction between his palms and the pole is $0.8$ and $g = 10 \,m/s^2$, the horizontal force that he is applying on the pole is: (in $\,N$)

The coefficient of friction between the block of mass ${M_1}$ and the surface is $\mu$. When the system is released,it moves with acceleration. What mass $m$ should be placed on the block ${M_1}$ so that the system moves with a constant velocity?

$A$ conveyor belt is moving at a constant speed of $2\, m s^{-1}$. $A$ 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 $g = 10\, m s^{-2}$,is ........... $m$.

$A$ $2 \, kg$ block on ice is given a velocity of $6 \, m/s$. If it comes to rest in $10 \, s$,what is the coefficient of friction?

$A$ block of mass $m=2 \ kg$ is initially at rest on a horizontal surface. $A$ horizontal force $F_1=(6 \ N) \hat{i}$ and a vertical force $F_2=(10 \ N) \hat{j}$ are then applied to the block. The coefficients of static friction and kinetic friction for the block and the surface are $0.4$ and $0.25$, respectively. The magnitude of the frictional force acting on the block is (assume $g=10 \ m/s^2$): (in $N$)

$A$ heavy box is pushed across a rough floor with an initial speed of $4 \, m/s$. It stops moving after $8 \, s$. If the average resisting force of friction is $10 \, N$,the mass of the box (in $kg$) is: