| Exam Board | OCR MEI |
|---|---|
| Module | M1 (Mechanics 1) |
| Year | 2008 |
| Session | June |
| Marks | 4 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Pulley systems |
| Type | Applied force in addition to weights |
| Difficulty | Moderate -0.3 This is a straightforward two-body connected particles problem requiring Newton's second law applied to the system to find acceleration, then to one body to find tension. It's slightly easier than average because the setup is simple (horizontal plane, no friction complications), involves only basic force resolution in one direction, and is a standard textbook exercise type with no novel insight required. |
| Spec | 3.03o Advanced connected particles: and pulleys |
| Answer | Marks | Guidance |
|---|---|---|
| Answer | Mark | Guidance |
| Overall, N2L \(\rightarrow\): \(135 - 9 = (5+4)a\) | M1 | Use of N2L. Allow \(F = mga\) but no extra forces. Allow 9 omitted |
| \(a = 14\) so \(14\) m s\(^{-2}\) | A1 | |
| For A, N2L \(\rightarrow\): \(T - 9 = 4\times14\), so 65 N | M1 | N2L on A or B with correct mass. \(F = ma\). All relevant forces and no extras |
| A1 | cao | |
| or \(135 - T = 5a\); \(T - 9 = 4a\); Solving; \(T = 65\) so 65 N | M1, A1, M1, A1 | *1 equation in \(T\) and \(a\). Both equations correct and consistent. Dependent on M* solving for \(T\). cao |
# Question 5:
| Answer | Mark | Guidance |
|--------|------|----------|
| Overall, N2L $\rightarrow$: $135 - 9 = (5+4)a$ | M1 | Use of N2L. Allow $F = mga$ but no extra forces. Allow 9 omitted |
| $a = 14$ so $14$ m s$^{-2}$ | A1 | |
| For A, N2L $\rightarrow$: $T - 9 = 4\times14$, so 65 N | M1 | N2L on A or B with correct mass. $F = ma$. All relevant forces and no extras |
| | A1 | cao |
| **or** $135 - T = 5a$; $T - 9 = 4a$; Solving; $T = 65$ so 65 N | M1, A1, M1, A1 | *1 equation in $T$ and $a$. Both equations correct and consistent. Dependent on M* solving for $T$. cao |
---5 Boxes A and B slide on a smooth, horizontal plane. Box A has a mass of 4 kg and box B a mass of 5 kg . They are connected by a light, inextensible, horizontal wire. Horizontal forces of 9 N and 135 N act on A and B in the directions shown in Fig. 5.
\begin{figure}[h]
\begin{center}
\includegraphics[alt={},max width=\textwidth]{170edb27-324e-44df-8dc1-7d8fbad680fe-3_91_913_1959_616}
\captionsetup{labelformat=empty}
\caption{Fig. 5}
\end{center}
\end{figure}
Calculate the tension in the wire joining the boxes.
\hfill \mbox{\textit{OCR MEI M1 2008 Q5 [4]}}