AQA M1 2009 June — Question 7 12 marks

Exam BoardAQA
ModuleM1 (Mechanics 1)
Year2009
SessionJune
Marks12
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicSUVAT in 2D & Gravity
TypeParticle motion: 2D constant acceleration
DifficultyModerate -0.8 This is a straightforward multi-part SUVAT question in 2D requiring only direct application of standard kinematic equations (v = u + at, s = ut + ½at²) with vector components. All parts are routine calculations with no problem-solving insight needed, making it easier than average but not trivial due to the vector notation and multiple parts.
Spec1.10e Position vectors: and displacement3.02e Two-dimensional constant acceleration: with vectors3.02g Two-dimensional variable acceleration

7 A particle moves on a smooth horizontal plane. It is initially at the point \(A\), with position vector \(( 9 \mathbf { i } + 7 \mathbf { j } ) \mathrm { m }\), and has velocity \(( - 2 \mathbf { i } + 2 \mathbf { j } ) \mathrm { m } \mathrm { s } ^ { - 1 }\). The particle moves with a constant acceleration of \(( 0.25 \mathbf { i } + 0.3 \mathbf { j } ) \mathrm { m } \mathrm { s } ^ { - 2 }\) for 20 seconds until it reaches the point \(B\). The unit vectors \(\mathbf { i }\) and \(\mathbf { j }\) are directed east and north respectively.
  1. Find the velocity of the particle at the point \(B\).
  2. Find the velocity of the particle when it is travelling due north.
  3. Find the position vector of the point \(B\).
  4. Find the average velocity of the particle as it moves from \(A\) to \(B\).
    \includegraphics[max width=\textwidth, alt={}]{c022c936-72bc-4cf9-8f98-285f12c1d479-15_2484_1709_223_153}

Question 7:
Part (a)
AnswerMarks Guidance
Working/AnswerMark Guidance
\(\mathbf{v} = \mathbf{u} + \mathbf{a}t\)M1 Correct formula used
\(\mathbf{v} = (-2\mathbf{i}+2\mathbf{j}) + 20(0.25\mathbf{i}+0.3\mathbf{j})\)A1 Correct substitution
\(\mathbf{v} = 3\mathbf{i} + 8\mathbf{j}\) m s\(^{-1}\)A1 Correct answer
Part (b)
AnswerMarks Guidance
Working/AnswerMark Guidance
Travelling due north means \(\mathbf{i}\) component \(= 0\)M1 Correct condition stated
\(-2 + 0.25t = 0\)A1 Correct equation
\(t = 8\) sA1 Correct time
\(\mathbf{v} = (2 + 0.3 \times 8)\mathbf{j} = 4.4\mathbf{j}\) m s\(^{-1}\)A1 Correct velocity
Part (c)
AnswerMarks Guidance
Working/AnswerMark Guidance
\(\mathbf{r} = \mathbf{r}_0 + \mathbf{u}t + \frac{1}{2}\mathbf{a}t^2\)M1 Correct formula
\(\mathbf{r} = (9\mathbf{i}+7\mathbf{j}) + 20(-2\mathbf{i}+2\mathbf{j}) + \frac{1}{2}(0.25\mathbf{i}+0.3\mathbf{j})(400)\)A1 Correct substitution
\(\mathbf{r} = (9-40+50)\mathbf{i} + (7+40+60)\mathbf{j} = 19\mathbf{i} + 107\mathbf{j}\) mA1 Correct answer
Part (d)
AnswerMarks Guidance
Working/AnswerMark Guidance
Average velocity \(= \frac{\Delta \mathbf{r}}{\Delta t} = \frac{(19\mathbf{i}+107\mathbf{j})-(9\mathbf{i}+7\mathbf{j})}{20}\)M1 Correct method
\(= \frac{10\mathbf{i}+100\mathbf{j}}{20} = 0.5\mathbf{i} + 5\mathbf{j}\) m s\(^{-1}\)A1 Correct answer
# Question 7:

## Part (a)
| Working/Answer | Mark | Guidance |
|---|---|---|
| $\mathbf{v} = \mathbf{u} + \mathbf{a}t$ | M1 | Correct formula used |
| $\mathbf{v} = (-2\mathbf{i}+2\mathbf{j}) + 20(0.25\mathbf{i}+0.3\mathbf{j})$ | A1 | Correct substitution |
| $\mathbf{v} = 3\mathbf{i} + 8\mathbf{j}$ m s$^{-1}$ | A1 | Correct answer |

## Part (b)
| Working/Answer | Mark | Guidance |
|---|---|---|
| Travelling due north means $\mathbf{i}$ component $= 0$ | M1 | Correct condition stated |
| $-2 + 0.25t = 0$ | A1 | Correct equation |
| $t = 8$ s | A1 | Correct time |
| $\mathbf{v} = (2 + 0.3 \times 8)\mathbf{j} = 4.4\mathbf{j}$ m s$^{-1}$ | A1 | Correct velocity |

## Part (c)
| Working/Answer | Mark | Guidance |
|---|---|---|
| $\mathbf{r} = \mathbf{r}_0 + \mathbf{u}t + \frac{1}{2}\mathbf{a}t^2$ | M1 | Correct formula |
| $\mathbf{r} = (9\mathbf{i}+7\mathbf{j}) + 20(-2\mathbf{i}+2\mathbf{j}) + \frac{1}{2}(0.25\mathbf{i}+0.3\mathbf{j})(400)$ | A1 | Correct substitution |
| $\mathbf{r} = (9-40+50)\mathbf{i} + (7+40+60)\mathbf{j} = 19\mathbf{i} + 107\mathbf{j}$ m | A1 | Correct answer |

## Part (d)
| Working/Answer | Mark | Guidance |
|---|---|---|
| Average velocity $= \frac{\Delta \mathbf{r}}{\Delta t} = \frac{(19\mathbf{i}+107\mathbf{j})-(9\mathbf{i}+7\mathbf{j})}{20}$ | M1 | Correct method |
| $= \frac{10\mathbf{i}+100\mathbf{j}}{20} = 0.5\mathbf{i} + 5\mathbf{j}$ m s$^{-1}$ | A1 | Correct answer |

---
7 A particle moves on a smooth horizontal plane. It is initially at the point $A$, with position vector $( 9 \mathbf { i } + 7 \mathbf { j } ) \mathrm { m }$, and has velocity $( - 2 \mathbf { i } + 2 \mathbf { j } ) \mathrm { m } \mathrm { s } ^ { - 1 }$. The particle moves with a constant acceleration of $( 0.25 \mathbf { i } + 0.3 \mathbf { j } ) \mathrm { m } \mathrm { s } ^ { - 2 }$ for 20 seconds until it reaches the point $B$. The unit vectors $\mathbf { i }$ and $\mathbf { j }$ are directed east and north respectively.
\begin{enumerate}[label=(\alph*)]
\item Find the velocity of the particle at the point $B$.
\item Find the velocity of the particle when it is travelling due north.
\item Find the position vector of the point $B$.
\item Find the average velocity of the particle as it moves from $A$ to $B$.\\

\begin{center}
\includegraphics[max width=\textwidth, alt={}]{c022c936-72bc-4cf9-8f98-285f12c1d479-15_2484_1709_223_153}
\end{center}
\end{enumerate}

\hfill \mbox{\textit{AQA M1 2009 Q7 [12]}}