Q. A coin of mass $10\ kg$ is placed over a book of length $50\ cm$. The coin is on the verge of sliding when one end of the book is lifted $10\ cm$ up. The coefficient of static friction between the book and the coin is
A) 1.0
B) 0.4
C) 0.3
D) 0.2
Explanation
(d) Tangent of angle of repose = coefficient of static friction
$\mu_{s} = \tan\theta$
$\mu_{s} \approx \frac{10}{50}$
$\approx 0.2$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.