| Exam Board | OCR MEI |
|---|---|
| Module | M1 (Mechanics 1) |
| Marks | 5 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Constant acceleration (SUVAT) |
| Type | Find acceleration from distances/times |
| Difficulty | Moderate -0.3 This is a straightforward two-part SUVAT problem requiring application of standard kinematic equations with given values. Part (i) uses s=ut+½at² to find acceleration, part (ii) uses v²=u²+2as then v=u+at. All values are provided clearly, requiring only systematic substitution into familiar formulas with no conceptual challenges or problem-solving insight needed. |
| Spec | 3.02d Constant acceleration: SUVAT formulae |
| Answer | Marks | Guidance |
|---|---|---|
| At C: \(s = ut + \frac{1}{2}at^2\) | ||
| \(500 = 5 \times 20 + 0.5 \times a \times 20^2\) | M1 | M1 for a method which if correctly applied would give \(a\) |
| \(a = 2 \text{ ms}^{-2}\) | A1 | Cao. Special case: If 800 is used for \(s\) instead of 500, giving \(a = 3.5\), treat as misread. Annotate SC SC and give M1 A0 |
| [2] |
| Answer | Marks | Guidance |
|---|---|---|
| At B: \(v^2 - u^2 = 2as\) | M1 | M1 for a method which if correctly applied would give either \(v\) or \(t\). Apply FT from incorrect \(a\) from part (i) for the M mark only |
| \(v^2 - 5^2 = 2 \times 2 \times 300\) | ||
| \(v = 35\), Speed is \(35 \text{ m s}^{-1}\) | A1 | Cao. No FT from part (i) except for SC1 for 46.2 following \(a = 3.5\) after use of \(s = 800\) |
| At B: \(v = u + at\) | ||
| \(35 = 5 + 2 \times t\) | ||
| \(t = 15\), Time is \(15 \text{ s}\) | A1 | Cao. No FT from part (i) except for SC1 for 11.7 following \(a = 3.5\) after use of \(s = 800\) |
| [3] |
## Question 4(i):
At C: $s = ut + \frac{1}{2}at^2$ | | |
$500 = 5 \times 20 + 0.5 \times a \times 20^2$ | M1 | M1 for a method which if correctly applied would give $a$ |
$a = 2 \text{ ms}^{-2}$ | A1 | Cao. **Special case**: If 800 is used for $s$ instead of 500, giving $a = 3.5$, treat as misread. Annotate SC SC and give M1 A0 |
| [2] | |
## Question 4(ii):
At B: $v^2 - u^2 = 2as$ | M1 | M1 for a method which if correctly applied would give either $v$ or $t$. Apply FT from incorrect $a$ from part (i) for the M mark only |
$v^2 - 5^2 = 2 \times 2 \times 300$ | | |
$v = 35$, Speed is $35 \text{ m s}^{-1}$ | A1 | Cao. No FT from part (i) except for SC1 for 46.2 following $a = 3.5$ after use of $s = 800$ |
At B: $v = u + at$ | | |
$35 = 5 + 2 \times t$ | | |
$t = 15$, Time is $15 \text{ s}$ | A1 | Cao. No FT from part (i) except for SC1 for 11.7 following $a = 3.5$ after use of $s = 800$ |
| [3] | |4 Fig. 4 illustrates points $\mathrm { A } , \mathrm { B }$ and C on a straight race track. The distance AB is 300 m and AC is 500 m .\\
A car is travelling along the track with uniform acceleration.
\begin{figure}[h]
\begin{center}
\includegraphics[alt={},max width=\textwidth]{b9e41fac-9f4b-4165-af03-67ebdcb326de-2_90_1335_982_331}
\captionsetup{labelformat=empty}
\caption{Fig. 4}
\end{center}
\end{figure}
Initially the car is at A and travelling in the direction AB with speed $5 \mathrm {~ms} ^ { - 1 }$. After 20s it is at C .\\
(i) Find the acceleration of the car.\\
(ii) Find the speed of the car at B and how long it takes to travel from A to B .
\hfill \mbox{\textit{OCR MEI M1 Q4 [5]}}