| Exam Board | AQA |
|---|---|
| Module | Paper 2 (Paper 2) |
| Year | 2018 |
| Session | June |
| Marks | 14 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Forces, equilibrium and resultants |
| Type | Connected particles via tow-bar on horizontal surface |
| Difficulty | Moderate -0.3 This is a standard A-level mechanics question involving Newton's second law applied to connected particles, followed by kinematics. Parts (a) and (b) require routine application of F=ma to find resistance and tension. Part (c) involves comparing stopping distances using v²=u²+2as. While multi-step, all techniques are standard textbook exercises with no novel insight required, making it slightly easier than average. |
| Spec | 3.02d Constant acceleration: SUVAT formulae3.03d Newton's second law: 2D vectors3.03k Connected particles: pulleys and equilibrium |
| Answer | Marks |
|---|---|
| 17(a)(i) | Forms equation of motion with |
| Answer | Marks | Guidance |
|---|---|---|
| Condone sign error | AO3.4 | M1 |
| Answer | Marks | Guidance |
|---|---|---|
| Obtains correct equation. | AO1.1b | A1 |
| Obtains correct value of R. | AO1.1b | A1 |
| Answer | Marks |
|---|---|
| 17(a)(ii) | Forms equation of motion with |
| Answer | Marks | Guidance |
|---|---|---|
| Condone sign error | AO1.1a | M1 |
| Answer | Marks | Guidance |
|---|---|---|
| Follow through their R | AO1.1b | A1F |
| Obtains correct value of T | AO1.1b | A1 |
| Answer | Marks | Guidance |
|---|---|---|
| 17(b) | States appropriate assumption | |
| NOT friction or air resistance | AO3.3 | E1 |
| Answer | Marks |
|---|---|
| 17(c)(i) | Forms equation of motion for |
| Answer | Marks | Guidance |
|---|---|---|
| Condone sign error | AO3.1b | M1 |
| Answer | Marks | Guidance |
|---|---|---|
| ‘their’ R | AO1.1b | A1F |
| Answer | Marks | Guidance |
|---|---|---|
| acceleration formula with ‘their’ a | AO1.1a | M1 |
| Answer | Marks | Guidance |
|---|---|---|
| s 20 | AO1.1b | A1F |
| Answer | Marks | Guidance |
|---|---|---|
| buggy using correct values | AO3.2a | E1 |
| Answer | Marks | Guidance |
|---|---|---|
| 17(c)(ii) | Explains that the tension is | |
| removed from the buggy | AO2.4 | E1 |
| Answer | Marks | Guidance |
|---|---|---|
| an increase in acceleration | AO2.4 | E1 |
| Total | 14 | |
| TOTAL | 100 |
Question 17:
--- 17(a)(i) ---
17(a)(i) | Forms equation of motion with
four correct terms
Condone sign error | AO3.4 | M1 | 300 – 140 – R = 482 x 0.2
R = 63.6 N
Obtains correct equation. | AO1.1b | A1
Obtains correct value of R. | AO1.1b | A1
--- 17(a)(ii) ---
17(a)(ii) | Forms equation of motion with
correct terms
Condone sign error | AO1.1a | M1 | T – 63.6 = 72 x 0.2
T = 78 N
Obtains correct equation
Follow through their R | AO1.1b | A1F
Obtains correct value of T | AO1.1b | A1
--- 17(b) ---
17(b) | States appropriate assumption
NOT friction or air resistance | AO3.3 | E1 | Rope has no mass or is horizontal
or is inextensible
--- 17(c)(i) ---
17(c)(i) | Forms equation of motion for
skater using ‘their’ R
Condone sign error | AO3.1b | M1 | -63.6 = 72a
a = -0.883… m s-2
u = 6 v =0 a = -0.883
062 20.883s
s = 20.4 m
20.4 > 20
Skater hits buggy
Finds correct acceleration for
‘their’ R | AO1.1b | A1F
Uses a suitable constant
acceleration formula with ‘their’ a | AO1.1a | M1
Obtains s when v0
Or
Obtains v or positive v2 when
s 20 | AO1.1b | A1F
Explains that the skater hits
buggy using correct values | AO3.2a | E1
--- 17(c)(ii) ---
17(c)(ii) | Explains that the tension is
removed from the buggy | AO2.4 | E1 | The rope is released so there is no
tension acting on the buggy, so
there is a higher resultant force.
The driver will notice an increase in
acceleration.
Explains that the driver notices
an increase in acceleration | AO2.4 | E1
Total | 14
TOTAL | 100A buggy is pulling a roller-skater, in a straight line along a horizontal road, by means of a connecting rope as shown in the diagram.
\includegraphics{figure_6}
The combined mass of the buggy and driver is 410 kg
A driving force of 300 N and a total resistance force of 140 N act on the buggy.
The mass of the roller-skater is 72 kg
A total resistance force of R newtons acts on the roller-skater.
The buggy and the roller-skater have an acceleration of 0.2 m s$^{-2}$
\begin{enumerate}[label=(\alph*)]
\item \begin{enumerate}[label=(\roman*)]
\item Find R.
[3 marks]
\item Find the tension in the rope.
[3 marks]
\end{enumerate}
\item State a necessary assumption that you have made.
[1 mark]
\item The roller-skater releases the rope at a point A, when she reaches a speed of 6 m s$^{-1}$
She continues to move forward, experiencing the same resistance force.
The driver notices a change in motion of the buggy, and brings it to rest at a distance of 20 m from A.
\begin{enumerate}[label=(\roman*)]
\item Determine whether the roller-skater will stop before reaching the stationary buggy.
Fully justify your answer.
[5 marks]
\item Explain the change in motion that the driver noticed.
[2 marks]
\end{enumerate}
\end{enumerate}
\hfill \mbox{\textit{AQA Paper 2 2018 Q17 [14]}}