Question

A coin is placed on a horizontal platform, which undergoes horizontal SHM about a mean position O. If the coin placed on platform does not slip, coefficient of friction between the coin and the platform is $\mu $ . The amplitude of oscillation is gradually increased. The coin will begin to slip on the platform for the first time

• A. at the mean position
• B. at the extreme position of oscillations
• C. for an amplitude of $\mu $ g/ $\omega ^{2}$
• D. for an amplitude of g/ $\mu \, \omega ^{2}$

Answer 1

Answer: (C)

Let $O$ be the mean position and $x$ be the distance of coin from $O$ . The coin will slip if centrifugal force on coin just becomes equal to force of friction $ie, \, mx\omega ^{2}=\mu mg$
The coin will slip if $x=$ maximum $=$ amplitude $A$