Question

A block of mass $m$ is placed on a rough inclined plane, whose coefficient of static friction is $\mu$, at an angle $\theta$.The angle of inclination is slowly increased. Find out the angle at which the block starts moving.

Answer 1

$0\le f\le {\mu }_{s}N$
$mgsin\theta >f_{smax}$
$mgsin\theta >\mu N$
$mgsin\theta >\mu cos\theta$
$\therefore tan\theta >\mu$
$\theta =ta{n}^{-1}\mu$
for tan $\theta \le \mu$ no sliding on inclined plane.
This method is used for finding out the value of $\mu$ practically