| Exam Board | Edexcel |
|---|---|
| Module | M1 (Mechanics 1) |
| Year | 2004 |
| Session | November |
| Marks | 8 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Moments |
| Type | Beam on point of tilting |
| Difficulty | Moderate -0.3 This is a standard M1 moments question with two straightforward parts: (a) taking moments about one point to find a reaction, and (b) using the 'point of tilting' condition (one reaction = 0) to find an unknown mass. Both parts follow textbook procedures with clear setups and minimal computational complexity, making it slightly easier than average for A-level. |
| Spec | 3.04a Calculate moments: about a point3.04b Equilibrium: zero resultant moment and force |
\includegraphics{figure_2}
A plank of wood $AB$ has mass 10 kg and length 4 m. It rests in a horizontal position on two smooth supports. One support is at the end $A$. The other is at the point $C$, 0.4 m from $B$, as shown in Figure 2. A girl of mass 30 kg stands at $B$ with the plank in equilibrium. By modelling the plank as a uniform rod and the girl as a particle,
\begin{enumerate}[label=(\alph*)]
\item find the reaction on the plank at $A$. [4]
\end{enumerate}
The girl gets off the plank. A boulder of mass $m$ kg is placed on the plank at $A$ and a man of mass 80 kg stands on the plank at $B$. The plank remains in equilibrium and is on the point of tilting about $C$. By modelling the plank again as a uniform rod, and the man and the boulder as particles,
\begin{enumerate}[label=(\alph*)]
\setcounter{enumi}{1}
\item find the value of $m$. [4]
\end{enumerate}
\hfill \mbox{\textit{Edexcel M1 2004 Q3 [8]}}