Laws of Motion: JEE Main 2026 Physics question

Two blocks (P and Q) with respectively masses 2 kg and 1.5 kg are joined by a massless thread. These blocks are mounted on a frictionless pully which is fixed on the edge of a cube (S), as shown in the figure below. Block P is positioned on the top surface which has no friction and block Q is in contact with side-surface, having coefficient friction $\mu$. The cube (S) moves towards the right with acceleration of $\frac g2$, where $g$ is gravitational acceleration. During this movement the block P and Q remain stationary. The value of $\mu$ is ________. (take $g=10\ \mathrm{m/s^2}$)