| Exam Board | Edexcel |
|---|---|
| Module | M2 (Mechanics 2) |
| Marks | 9 |
| Paper | Download PDF ↗ |
| Topic | Centre of Mass 1 |
| Type | Lamina with removed circle/semicircle |
| Difficulty | Standard +0.3 This is a standard M2 centre of mass question requiring the formula for composite bodies (part a) and equilibrium of a suspended lamina (part b). Both parts follow routine procedures taught in the module with no novel insight required, making it slightly easier than average. |
| Spec | 6.04c Composite bodies: centre of mass |
\includegraphics{figure_1}
Figure 1 shows a decoration which is made by cutting 2 circular discs from a sheet of uniform card. The discs are joined so that they touch at a point $D$ on the circumference of both discs. The discs are coplanar and have centres $A$ and $B$ with radii 10 cm and 20 cm respectively.
\begin{enumerate}[label=(\alph*)]
\item Find the distance of the centre of mass of the decoration from $B$.
[5]
\end{enumerate}
The point $C$ lies on the circumference of the smaller disc and $\angle CAB$ is a right angle. The decoration is freely suspended from $C$ and hangs in equilibrium.
\begin{enumerate}[label=(\alph*)]
\setcounter{enumi}{1}
\item Find, in degrees to one decimal place, the angle between $AB$ and the vertical.
[4]
\end{enumerate}
\hfill \mbox{\textit{Edexcel M2 Q2 [9]}}