| Exam Board | AQA |
|---|---|
| Module | AS Paper 1 (AS Paper 1) |
| Year | 2018 |
| Session | June |
| Marks | 6 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Constant acceleration (SUVAT) |
| Type | Reaction time and stopping distance |
| Difficulty | Moderate -0.3 This is a straightforward AS-level mechanics question requiring basic understanding of forces and SUVAT equations. Part (a) tests conceptual understanding of air resistance/drafting (1 mark recall). Part (b)(i) involves standard kinematics: convert units, find deceleration from F=ma, then use v²=u²+2as to find stopping distance—routine multi-step calculation with no novel insight required. Part (b)(ii) asks for a modeling assumption, which is standard bookwork. Slightly easier than average due to straightforward application of standard techniques. |
| Spec | 3.03c Newton's second law: F=ma one dimension |
| Answer | Marks |
|---|---|
| 15(a) | States that the resistance is less |
| Answer | Marks | Guidance |
|---|---|---|
| OE | AO2.4 | E1 |
| Answer | Marks |
|---|---|
| 15(b)(i) | Models situation by using given |
| Answer | Marks | Guidance |
|---|---|---|
| to form equation of motion PI | AO3.3 | M1 |
| Answer | Marks | Guidance |
|---|---|---|
| May include u = 25. | AO3.4 | M1 |
| Answer | Marks | Guidance |
|---|---|---|
| s = 40 | AO1.1b | A1 |
| Answer | Marks | Guidance |
|---|---|---|
| other variables must be clear. | AO3.2a | E1 |
| Answer | Marks |
|---|---|
| 15(b)(ii) | States an assumption that, if |
| Answer | Marks | Guidance |
|---|---|---|
| as speed drops OE) | AO3.5a | E1F |
| Answer | Marks | Guidance |
|---|---|---|
| Total | 6 | |
| Q | Marking Instructions | AO |
Question 15:
--- 15(a) ---
15(a) | States that the resistance is less
for the second rider so the force
required for equilibrium is also
less, or mention of slipstreaming
OE | AO2.4 | E1 | Jason experiences less air
resistance than Laura.
--- 15(b)(i) ---
15(b)(i) | Models situation by using given
mass and total resistance force
to form equation of motion PI | AO3.3 | M1 | As F = ma then a = - 0.625 m s-2
u = 25 km/h = 6.944 m s-1
v = 0; use v2 = u2 + 2as so that
0 = 6.9442 + 2 x (-0.625) x s
s = 38.6 m
So Laura stops before reaching the
accident
Uses appropriate suvat formula.
May include u = 25. | AO3.4 | M1
States correct value for s
(AWFW 38.5 to 38.6)
Or maximum u = 7.07 m s-1
or 25.5 km/h (AWRT)
Or a needs to be < -0.603
(AWRT)
Or Resistance needs to be
>38.5 N (AWFW 38.4 to 38.6)
Or v2 is -1.8 (AWRT) when
s = 40 | AO1.1b | A1
Makes appropriate comparison
to conclude that Laura stops in
time. Not necessary to see
38.6 < 40, but comparison for
other variables must be clear. | AO3.2a | E1
--- 15(b)(ii) ---
15(b)(ii) | States an assumption that, if
incorrect, would contradict the
conclusion in (i). (eg reaction
time, diminishing resistive force
as speed drops OE) | AO3.5a | E1F | Taking account of reaction time
would mean she travelled a
distance before starting to brake.
Total | 6
Q | Marking Instructions | AO | Marks | Typical SolutionA cyclist, Laura, is travelling in a straight line on a horizontal road at a constant speed of $25\,\mathrm{km}\,\mathrm{h}^{-1}$
A second cyclist, Jason, is riding closely and directly behind Laura. He is also moving with a constant speed of $25\,\mathrm{km}\,\mathrm{h}^{-1}$
\begin{enumerate}[label=(\alph*)]
\item The driving force applied by Jason is likely to be less than the driving force applied by Laura.
Explain why.
[1 mark]
\item Jason has a problem and stops, but Laura continues at the same constant speed.
Laura sees an accident $40\,\mathrm{m}$ ahead, so she stops pedalling and applies the brakes.
She experiences a total resistance force of $40\,\mathrm{N}$
Laura and her cycle have a combined mass of $64\,\mathrm{kg}$
\begin{enumerate}[label=(\roman*)]
\item Determine whether Laura stops before reaching the accident.
Fully justify your answer.
[4 marks]
\item State one assumption you have made that could affect your answer to part (b)(i).
[1 mark]
\end{enumerate}
\end{enumerate}
\hfill \mbox{\textit{AQA AS Paper 1 2018 Q15 [6]}}