Question

Block $M$ slides down on a frictionless inclined plane as shown in the figure. What is the minimum coefficient of friction so that $m$ does not slide with respect to $M$?

• A. 4/3
• B. 1
• C. 3/4
• D. 3 /5

Answer 1

Answer: (C)

3/4

Given both the block are at rest with respect to each other so let us solve the problem in the frame of M which is moving along the incline with $g\times sin37$.
Let the friction be f, then by applying newton's second law along the incline and perpendicular to it we have,
$f\times sin37+N\times cos37=m\times g\times cos37$
$f\times cos37=N\times sin37$
Solving them will give,
$f=3/4$