| Exam Board | Edexcel |
|---|---|
| Module | M2 (Mechanics 2) |
| Marks | 15 |
| Paper | Download PDF ↗ |
| Topic | Projectiles |
| Type | Projection from elevated point - angle above horizontal |
| Difficulty | Standard +0.8 This is a substantial M2 projectiles question combining multiple concepts: standard projectile motion to find maximum height and time, conservation of momentum in 2D after an explosion, and subsequent projectile motion. While each individual step uses standard techniques (resolving velocity components, using v=u+at, momentum conservation), the multi-stage nature with 15 total marks and the need to track two particles after explosion makes it more demanding than typical M2 questions. The 'show that' part (c) provides scaffolding, preventing this from being truly difficult. |
| Spec | 3.02h Motion under gravity: vector form3.02i Projectile motion: constant acceleration model6.03b Conservation of momentum: 1D two particles |
\includegraphics{figure_3}
A rocket $R$ of mass 100 kg is projected from a point $A$ with speed 80 m s$^{-1}$ at an angle of elevation of $60°$, as shown in Fig. 3. The point $A$ is 20 m vertically above a point $O$ which is on horizontal ground. The rocket $R$ moves freely under gravity. At $B$ the velocity of $R$ is horizontal. By modelling $R$ as a particle, find
\begin{enumerate}[label=(\alph*)]
\item the height in m of $B$ above the ground,
[4]
\end{enumerate}
\begin{enumerate}[label=(\alph*)]
\setcounter{enumi}{1}
\item the time taken for $R$ to reach $B$ from $A$.
[2]
\end{enumerate}
When $R$ is at $B$, there is an internal explosion and $R$ breaks into two parts $P$ and $Q$ of masses 60 kg and 40 kg respectively. Immediately after the explosion the velocity of $P$ is 80 m s$^{-1}$ horizontally away from $A$. After the explosion the paths of $P$ and $Q$ remain in the plane $OAB$. Part $Q$ strikes the ground at $C$. By modelling $P$ and $Q$ as particles,
\begin{enumerate}[label=(\alph*)]
\setcounter{enumi}{2}
\item show that the speed of $Q$ immediately after the explosion is 20 m s$^{-1}$,
[3]
\end{enumerate}
\begin{enumerate}[label=(\alph*)]
\setcounter{enumi}{3}
\item find the distance $OC$.
[6]
\end{enumerate}
END
\hfill \mbox{\textit{Edexcel M2 Q7 [15]}}