A child weighing $25$ kg slides down a rope hanging from the branch of a tall tree. If the force of friction acting against him is $2\, N$,  ........ $m/s^2$ is the acceleration of the child (Take $g = 9.8\,m/{s^2})$

A block of mass $m$ rests on a rough inclined plane. The coefficient of friction between  the surface and the block is $\mu$. At what angle of inclination $\theta$ of the plane to  the horizontal will the block just start to slide down the plane?

A block of mass $m$ is stationary on a rough plane of mass $M$ inclined at an angle $\theta$ to the horizontal, while the whole set up is accelerating upwards at an acceleration $\alpha$. If the coefficient of friction between the block and the plane is $\mu$, then the force that the plane exerts on the block is

Someone is using a scissors to cut a wire of circular cross section and negligible weight. The wire slides in the direction away from the hinge until the angle between the scissors blades becomes $2 \alpha$. The friction coefficient between the blades and the wire, is :-

The maximum static frictional force is

When a bicycle is in motion, the force of friction exerted by the ground on the two wheels is such that it acts