Q 11-04-048NEETJEE MainMedium
A $4$ kg block on a rough horizontal table ($\mu_k = 0.25$) is connected by a light string over a smooth pulley at the table's edge to a $2$ kg block hanging freely. The acceleration of the system is ($g = 10\ \text{m/s}^2$)
Answer: (A) $\dfrac{5}{3}\ \text{m/s}^2$
Concept. Net driving force over total mass.
Step 1. Forces. Hanging weight $20$ N, friction $0.25 \times 40 = 10$ N.
Step 2. Acceleration. $\dfrac{10}{6} = \dfrac53\ \text{m/s}^2$.
Answer. $\dfrac53\ \text{m/s}^2$ (Option A).
Solution by Sreeraj P, M.Sc Physics