(i)[2]
Find the deceleration of each particle, given that the coefficient of friction between $P$ and the plane is $0.2$, and between $Q$ and the plane is $0.25$.
(ii)[5]
At a particular instant, $P$ passes through point $A$ and $Q$ passes through point $B$. The distance $AB$ is $5\,\mathrm{m}$. The velocities of $P$ and $Q$ at $A$ and $B$ are $8\,\mathrm{m\,s^{-1}}$ and $3\,\mathrm{m\,s^{-1}}$, respectively, both along the direction $AB$. Find the speeds of $P$ and $Q$ immediately before they collide.