Q 11-04-038NEETJEE MainEasy
A block placed on a plank just begins to slide when the plank is tilted to $30°$ with the horizontal. The coefficient of static friction between the block and the plank is
Answer: (C) $\dfrac{1}{\sqrt{3}}$
At the angle of repose, $mg\sin\theta = \mu_s mg\cos\theta$:
$$\mu_s = \tan 30° = \frac{1}{\sqrt{3}}$$
Solution by Sreeraj P, M.Sc Physics