4. A particle $P$ moves in a straight line with constant velocity. Initially $P$ is at the point $A$ with position vector $( 2 \mathbf { i } - \mathbf { j } ) \mathrm { m }$ relative to a fixed origin $O$, and 2 s later it is at the point $B$ with position vector $( 6 \mathbf { i } + \mathbf { j } ) \mathrm { m }$.
\begin{enumerate}[label=(\alph*)]
\item Find the velocity of $P$.
\item Find, in degrees to one decimal place, the size of the angle between the direction of motion of $P$ and the vector $\mathbf { i }$.

Three seconds after it passes $B$ the particle $P$ reaches the point $C$.
\item Find, in m to one decimal place, the distance $O C$.
\end{enumerate}

\hfill \mbox{\textit{Edexcel M1  Q4 [7]}}