A block of mass $2 kg$ slides down an incline plane of inclination $30^o$. The coefficient of friction between block and plane is $0.5$. The contact force between block and plank is :
$5\sqrt 15 Nt$
$10\sqrt 3\,Nt$
$5\sqrt 7 Nt$
$20 \,Nt$
Write unit of coefficient of static friction.
Why are mountain roads generally made winding upwards rather than going straight up ?
A body of mass $\mathrm{m}$ is kept on a rough horizontal surface (coefficient of friction $=\mu$ ) A horizontal force is applied on the body, but it does not move. The resultant of normal reaction and the frictional force acting on the object is given by $\mathrm{F},$ where $\mathrm{F}$ is
Why coefficient friction is considered as static friction ?
If the normal force is doubled, the coefficient of friction is