Physics Question from JEE Main 2025 · 3 April, Shift 1

Two blocks of masses $m$ and $M$, ($M > m$), are placed on a frictionless table as shown in figure. A massless spring with spring constant $k$ is attached with the lower block. If the system is slightly displaced and released then ($\mu$ = coefficient of friction between the two blocks)

A. The time period of small oscillation of the two blocks is $T = 2\pi\sqrt{\dfrac{m+M}{k}}$

B. The acceleration of the blocks is $a = \dfrac{kx}{M+m}$ ($x$ = displacement of the blocks from the mean position)

C. The magnitude of the frictional force on the upper block is $\dfrac{m\mu|x|}{M+m}$

D. The maximum amplitude of the upper block, if it does not slip, is $\dfrac{\mu(M+m)g}{k}$

E. Maximum frictional force can be $\mu(M+m)g$.

Choose the correct answer from the options given below :