| Exam Board | Edexcel |
|---|---|
| Module | M1 (Mechanics 1) |
| Marks | 6 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Moments |
| Type | Beam on point of tilting |
| Difficulty | Standard +0.3 This is a straightforward moments problem requiring students to take moments about the pivot point Z to find when the plank is on the point of toppling. The setup is clear, the method is standard (moments = 0 at equilibrium), and the calculation involves simple arithmetic with the plank's center of mass and the stone's position. Part (b) tests conceptual understanding but requires minimal additional work. Slightly easier than average due to its routine nature and clear diagram. |
| Spec | 3.04b Equilibrium: zero resultant moment and force6.04e Rigid body equilibrium: coplanar forces |
| Answer | Marks | Guidance |
|---|---|---|
| (a) \(M(Z): 0·7(2g) = 2·8(mg)\) with \(m = 0·5 \text{ kg}\) | M1 M1 A1 A1 | 4 marks |
| (b) Greater, as moment of weight larger and distance to stone less | B1 B1 | 2 marks total: 6 |
(a) $M(Z): 0·7(2g) = 2·8(mg)$ with $m = 0·5 \text{ kg}$ | M1 M1 A1 A1 | 4 marks
(b) Greater, as moment of weight larger and distance to stone less | B1 B1 | 2 marks total: 6A uniform plank $XY$ has length 7 m and mass 2 kg. It is placed with the portion $ZY$ in contact with a horizontal surface, where $ZY = 2.8$ m. To prevent the plank from toppling, a stone is placed on the plank at $Y$.
\includegraphics{figure_2}
\begin{enumerate}[label=(\alph*)]
\item Find the smallest possible mass of the stone. [4 marks]
\item State, with a reason, whether your answer to part (a) would be greater or smaller if a shorter portion of the plank were in contact with the surface. [2 marks]
\end{enumerate}
\hfill \mbox{\textit{Edexcel M1 Q2 [6]}}