May/June 2026 Paper 42

The points $A$ and $B$ are at the same vertical height $h\mathrm{m}$ above horizontal ground. A particle $P$ is released from rest from $A$. One second later, a particle $Q$ is projected vertically downwards from $B$ with speed $18m/s$. Given that $P$ and $Q$ reach the ground at the same time, find the value of $h$.