Q 11-04-070JEE MainJEE Main 2024 (1 Feb, Shift 1)Easy
Consider the block and trolley system shown in the figure. If the coefficient of kinetic friction between the trolley and the surface is $0.04$, the acceleration of the system in $\text{m s}^{-2}$ is (the string is massless and inextensible and the pulley is massless and frictionless; take $g = 10\ \text{m s}^{-2}$)
Answer: (C) $2$
Friction on the trolley: $f_k = \mu m g = 0.04\times20\times10 = 8\ \text{N}$.
The weight of the hanging block ($60\ \text{N}$) drives both masses:
$$a = \frac{60 - 8}{20 + 6} = \frac{52}{26} = 2\ \text{m s}^{-2}$$
Solution by Sreeraj P, M.Sc Physics