| Exam Board | AQA |
|---|---|
| Module | AS Paper 1 (AS Paper 1) |
| Year | 2018 |
| Session | June |
| Marks | 6 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Pulley systems |
| Type | Two particles over pulley, vertical strings |
| Difficulty | Moderate -0.8 This is a standard AS-level mechanics problem involving connected particles over a pulley. Part (a) requires setting up Newton's second law for both particles, finding acceleration, then using kinematics (s=ut+½at²) - all routine procedures covered extensively in textbooks. Part (b) is a simple recall of modeling assumptions. The 5-mark allocation and straightforward setup make this easier than average for A-level, though not trivial. |
| Spec | 3.03k Connected particles: pulleys and equilibrium |
| Answer | Marks |
|---|---|
| 14(a) | Forms two equations of motion for |
| Answer | Marks | Guidance |
|---|---|---|
| “Whole string” approach scores M0 | AO3.4 | M1 |
| Answer | Marks | Guidance |
|---|---|---|
| Obtains two correct equations | AO1.1b | A1 |
| Answer | Marks | Guidance |
|---|---|---|
| 0.2g or AWRT 1.96 | AO1.1b | A1 |
| Answer | Marks | Guidance |
|---|---|---|
| calculated 𝑎 value | AO1.1a | M1 |
| Answer | Marks | Guidance |
|---|---|---|
| AWRT 1.24 | AO1.1b | A1 |
| Answer | Marks |
|---|---|
| 14(b) | Any valid assumption stated. |
| Answer | Marks | Guidance |
|---|---|---|
| Air resistance is permitted. | AO3.5b | E1 |
| Answer | Marks | Guidance |
|---|---|---|
| Total | 6 | |
| Q | Marking Instructions | AO |
Question 14:
--- 14(a) ---
14(a) | Forms two equations of motion for
1.8 and 1.2 kg mass, three terms,
condone sign error.
“Whole string” approach scores M0 | AO3.4 | M1 | 1.8 x 9.81 – T = 1.8 x a
T – 1.2 x 9.81 = 1.2 x a
𝑎 = 1.96 m s-2
1.5 = ½ x 1.96 x 𝑡2
𝑡 = 1.24 seconds
Obtains two correct equations | AO1.1b | A1
Solves to find correct value for 𝑎
0.2g or AWRT 1.96 | AO1.1b | A1
Uses 𝑠 = 𝑢𝑡 + ½ 𝑎𝑡2 with their
calculated 𝑎 value | AO1.1a | M1
Calculates correct 𝑡 value
AWRT 1.24 | AO1.1b | A1
--- 14(b) ---
14(b) | Any valid assumption stated.
Do not allow any comment already
stated as an assumption in the
question.
Air resistance is permitted. | AO3.5b | E1 | The string is long enough so that
lighter mass does not reach the
peg before the heavier mass hits
the ground.
Total | 6
Q | Marking Instructions | AO | Marks | Typical SolutionIn this question use $g = 9.81\,\mathrm{m}\,\mathrm{s}^{-2}$
Two particles, of mass $1.8\,\mathrm{kg}$ and $1.2\,\mathrm{kg}$, are connected by a light, inextensible string over a smooth peg.
\includegraphics{figure_14}
\begin{enumerate}[label=(\alph*)]
\item Initially the particles are held at rest $1.5\,\mathrm{m}$ above horizontal ground and the string between them is taut.
The particles are released from rest.
Find the time taken for the $1.8\,\mathrm{kg}$ particle to reach the ground.
[5 marks]
\item State one assumption you have made in answering part (a).
[1 mark]
\end{enumerate}
\hfill \mbox{\textit{AQA AS Paper 1 2018 Q14 [6]}}