A block of mass $m$ slides along a floor while a force of magnitude $F$ is applied to it at an angle $\theta$ as shown in figure. The coefficient of kinetic friction is $\mu_{ K }$. Then, the block's acceleration $'a'$ is given by: ($g$ is acceleration due to gravity)

An insect crawls up a hemispherical surface very slowly. The coefficient of friction between the insect and the surface is $1/3$. If the line joining the centre of the hemispherical surface to the insect makes an angle $\alpha $ with the vertical, the maximum possible value of $\alpha $ so that the insect does not slip is given by

A block of mass $10\, kg$ starts sliding on a surface with an initial velocity of $9.8\, ms ^{-1}$. The coefficient of friction between the surface and bock is $0.5$. The distance covered by the block before coming to rest is: [use $g =9.8\, ms ^{-2}$ ]………$m$