Find the work done against friction in $J$ when a block of mass $50\, kg$ moves a distance of $1\, m$ on a rough horizontal surface with a coefficient of friction of $0.2$.

$A$ horizontal force of $40\,N$ is applied to a $5\,kg$ block which is at rest on a horizontal surface. If the coefficient of kinetic friction is $0.4$,then the acceleration of the block is ........ $m/s^2$ $(g = 10\,m/s^2)$.

$A$ fireman of mass $60 \ kg$ slides down a pole. He is pressing the pole with a force of $600 \ N$. The coefficient of friction between the hands and the pole is $0.5$. With what acceleration (in $m/s^2$) will the fireman slide down? (Take $g = 10 \ m/s^2$)

$A$ block of mass $5 \ kg$ is placed on a rough horizontal surface having a coefficient of friction $0.5$. If a horizontal force of $60 \ N$ is acting on it,then the acceleration of the block is (Acceleration due to gravity,$g = 10 \ ms^{-2}$). (in $ms^{-2}$)

$A$ vehicle of mass $M$ is moving with momentum $P$ on a rough horizontal road. The coefficient of friction between the tyres and the horizontal road is $\mu$. The stopping distance is ($g$ $=$ acceleration due to gravity).

Consider a block and trolley system as shown in the figure. If the coefficient of kinetic friction between the trolley and the surface is $0.04$,the acceleration of the system in $m/s^2$ is (Consider that the string is massless and unstretchable and the pulley is also massless and frictionless):