In this question use $g=9.8$ m s${}^{-2}$

Two particles $P$ and $Q$, of masses 0.5 kg and $m$ kg respectively, are connected by a light inextensible string.

The string passes over a smooth fixed pulley, and both particles hang freely with the string vertical on both sides of the pulley.

The system is released from rest with the string taut and with $P$ and $Q$ at the same height.

At the instant 1.5 seconds after release, $Q$ is 4.41 metres below $P$.