$A$ spring-block system is placed on a rough horizontal floor. The block is pulled towards the right to give the spring some elongation and then released. The block will have maximum velocity when:

$A$ uniform chain of length $L$ is lying on a horizontal table. If the coefficient of friction between the chain and the table top is $\mu$,what is the maximum length of the chain that can hang over the edge of the table without disturbing the rest of the chain on the table?

$A$ block of mass $\sqrt{2} \,kg$ is placed on a rough horizontal surface. $A$ force $F$ acting upwards at an angle of $45^{\circ}$ with the horizontal causes the block to start motion. If the coefficient of static friction between the surface and the block is $0.25$, the magnitude of the force $F$ is (Acceleration due to gravity $= 10 \,ms^{-2}$) (in $\,N$)

$A$ body is pulled along a rough horizontal surface with a velocity $6\,m/s$. If the body comes to rest after travelling $9\,m$,then the coefficient of sliding friction is- (Take $g = 10\,m/s^2$)

$A$ 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 $\,N$)

$A$ block of mass $50\, kg$ slides over a horizontal distance of $1\, m$. If the coefficient of friction between their surfaces is $0.2$,then the work done against friction is ......... $J$.