| Exam Board | OCR MEI |
|---|---|
| Module | Paper 1 (Paper 1) |
| Session | Specimen |
| Marks | 4 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Friction |
| Type | Practical friction scenarios |
| Difficulty | Moderate -0.3 This is a straightforward friction problem requiring resolution of forces and understanding of limiting friction. Part (a) involves basic trigonometry (100cos32°) with no problem-solving insight needed. Part (b) tests conceptual understanding that reducing the angle increases the horizontal component, thus increasing friction, but remains a standard textbook scenario requiring minimal reasoning beyond the mechanics syllabus fundamentals. |
| Spec | 3.03a Force: vector nature and diagrams3.03i Normal reaction force3.03r Friction: concept and vector form3.03u Static equilibrium: on rough surfaces |
| Answer | Marks |
|---|---|
| Horizontal component \(= 100 \times \cos 32°\) | M1 (3.3) |
| \(84.8\ \text{N}\) | A1 (1.1) |
| Answer | Marks |
|---|---|
| Frictional force is \(100\cos\theta\) [with \(\theta < 32°\)] | M1 (3.4) |
| So frictional force increases. (oe) | E1 (2.2a) |
## Question 5(a):
Horizontal component $= 100 \times \cos 32°$ | M1 (3.3) |
$84.8\ \text{N}$ | A1 (1.1) |
**Total: [2]**
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## Question 5(b):
Frictional force is $100\cos\theta$ [with $\theta < 32°$] | M1 (3.4) |
So frictional force increases. (oe) | E1 (2.2a) |
**Total: [2]**5 A woman is pulling a loaded sledge along horizontal ground. The only resistance to motion of the sledge is due to friction between it and the ground.
\begin{figure}[h]
\begin{center}
\includegraphics[alt={},max width=\textwidth]{ff44367e-c992-4e79-b255-5a04e0b8e21e-05_314_1024_486_356}
\captionsetup{labelformat=empty}
\caption{Fig. 5}
\end{center}
\end{figure}
At first, she pulls with a force of 100 N inclined at $32 ^ { \circ }$ to the horizontal, as shown in Fig.5, but the sledge does not move.
\begin{enumerate}[label=(\alph*)]
\item Determine the frictional force between the ground and the sledge.
Give your answer correct to 3 significant figures.
\item Next she pulls with a force of 100 N inclined at a smaller angle to the horizontal. The sledge still does not move.
Compare the frictional force in this new situation with that in part (a), justifying your answer.
\end{enumerate}
\hfill \mbox{\textit{OCR MEI Paper 1 Q5 [4]}}