| Exam Board | OCR MEI |
|---|---|
| Module | Paper 1 (Paper 1) |
| Year | 2020 |
| Session | November |
| Marks | 4 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Moments |
| Type | Beam on point of tilting |
| Difficulty | Moderate -0.5 This is a straightforward moments equilibrium problem requiring students to identify forces (weight of ruler, applied force, reaction at C), mark distances from the pivot point C, and take moments about C to solve for F. It involves standard mechanics techniques with clear setup and routine calculation, making it slightly easier than average but still requiring proper method. |
| Spec | 3.04a Calculate moments: about a point3.04b Equilibrium: zero resultant moment and force |
| Answer | Marks | Guidance |
|---|---|---|
| Answer | Marks | Guidance |
| \(F\) N and weight \(W\) N shown in roughly correct position | B1 | F and their weight even if not labelled in roughly correct position. R is already drawn in Printed Answer Booklet |
| Distances labelled: \(5\) cm from A to C, \(10\) cm from A to B | B1 [2] | Allow for 5 cm and any measurements that show that the weight is acting in the centre of the ruler |
| Answer | Marks | Guidance |
|---|---|---|
| Answer | Marks | Guidance |
| Take moments about C: \(10 \times 0.028g = 5F\) | M1 | Moments about any point with all relevant forces seen. Allow their weight and one incorrect distance. Allow \(\frac{7}{125}g\) oe. [Value of R is 0.8232 N] |
| \(F = 0.549\) N | A1 [2] |
## Question 6(a):
| Answer | Marks | Guidance |
|--------|-------|----------|
| $F$ N and weight $W$ N shown in roughly correct position | B1 | F and their weight even if not labelled in roughly correct position. R is already drawn in Printed Answer Booklet |
| Distances labelled: $5$ cm from A to C, $10$ cm from A to B | B1 [2] | Allow for 5 cm and any measurements that show that the weight is acting in the centre of the ruler |
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## Question 6(b):
| Answer | Marks | Guidance |
|--------|-------|----------|
| Take moments about C: $10 \times 0.028g = 5F$ | M1 | Moments about any point with all relevant forces seen. Allow their weight and one incorrect distance. Allow $\frac{7}{125}g$ oe. [Value of R is 0.8232 N] |
| $F = 0.549$ N | A1 [2] | |
---6 A uniform ruler AB has mass 28 g and length 30 cm . As shown in Fig. 6, the ruler is placed on a horizontal table so that it overhangs a point C at the edge of the table by 25 cm .
A downward force of $F \mathrm {~N}$ is applied at A . This force just holds the ruler in equilibrium so that the contact force between the table and the ruler acts through C .
\begin{figure}[h]
\begin{center}
\includegraphics[alt={},max width=\textwidth]{7de77679-59c0-4431-a9cb-6ab11d2f9062-05_188_1431_502_246}
\captionsetup{labelformat=empty}
\caption{Fig. 6}
\end{center}
\end{figure}
\begin{enumerate}[label=(\alph*)]
\item Complete the force diagram in the Printed Answer Booklet, labelling the forces and all relevant distances.
\item Calculate the value of $F$.
Answer all the questions.\\
Section B (78 marks)
\end{enumerate}
\hfill \mbox{\textit{OCR MEI Paper 1 2020 Q6 [4]}}