AQA M1 2005 June — Question 7 8 marks

Exam BoardAQA
ModuleM1 (Mechanics 1)
Year2005
SessionJune
Marks8
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicSUVAT in 2D & Gravity
TypeParticle motion: 2D direction/bearing
DifficultyModerate -0.3 This is a straightforward 2D kinematics question requiring standard application of v = u + at in vector form. Part (a) is direct substitution, part (b) requires setting the j-component to zero (routine), and part (c) is a simple verification using Pythagoras. Slightly easier than average due to the mechanical nature of the calculations with no conceptual challenges.
Spec1.10h Vectors in kinematics: uniform acceleration in vector form3.02g Two-dimensional variable acceleration

7 A particle moves on a smooth horizontal surface with acceleration \(( 3 \mathbf { i } - 5 \mathbf { j } ) \mathrm { ms } ^ { - 2 }\). Initially the velocity of the particle is \(4 \mathbf { j } \mathrm {~m} \mathrm {~s} ^ { - 1 }\).
  1. Find an expression for the velocity of the particle at time \(t\) seconds.
  2. Find the time when the particle is travelling in the \(\mathbf { i }\) direction.
  3. Show that when \(t = 4\) the speed of the particle is \(20 \mathrm {~ms} ^ { - 1 }\).

Question 7:
Part (a)
AnswerMarks Guidance
WorkingMarks Guidance
\(\mathbf{v}=4\mathbf{j}+(3\mathbf{i}-5\mathbf{j})t\)M1A1 Use of \(\mathbf{v}=\mathbf{u}+\mathbf{a}t\) and \(\mathbf{u}\neq0\) or integration; correct expression
Part (b)
AnswerMarks Guidance
WorkingMarks Guidance
\(\mathbf{v}=3t\mathbf{i}+(4-5t)\mathbf{j}\); \(4-5t=0\)M1 \(\mathbf{j}\) component of velocity equal to zero
\(t=0.8\text{ s}\)A1 Correct \(t\)
Part (c)
AnswerMarks Guidance
WorkingMarks Guidance
\(\mathbf{v}=12\mathbf{i}-16\mathbf{j}\)M1 Finding velocity when \(t=4\)
A1Correct velocity
\(v=\sqrt{12^2+16^2}=20\)dM1 Finding the magnitude
A1Correct speed from correct working
## Question 7:

**Part (a)**

| Working | Marks | Guidance |
|---------|-------|----------|
| $\mathbf{v}=4\mathbf{j}+(3\mathbf{i}-5\mathbf{j})t$ | M1A1 | Use of $\mathbf{v}=\mathbf{u}+\mathbf{a}t$ and $\mathbf{u}\neq0$ or integration; correct expression |

**Part (b)**

| Working | Marks | Guidance |
|---------|-------|----------|
| $\mathbf{v}=3t\mathbf{i}+(4-5t)\mathbf{j}$; $4-5t=0$ | M1 | $\mathbf{j}$ component of velocity equal to zero |
| $t=0.8\text{ s}$ | A1 | Correct $t$ |

**Part (c)**

| Working | Marks | Guidance |
|---------|-------|----------|
| $\mathbf{v}=12\mathbf{i}-16\mathbf{j}$ | M1 | Finding velocity when $t=4$ |
| | A1 | Correct velocity |
| $v=\sqrt{12^2+16^2}=20$ | dM1 | Finding the magnitude |
| | A1 | Correct speed from correct working |

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7 A particle moves on a smooth horizontal surface with acceleration $( 3 \mathbf { i } - 5 \mathbf { j } ) \mathrm { ms } ^ { - 2 }$. Initially the velocity of the particle is $4 \mathbf { j } \mathrm {~m} \mathrm {~s} ^ { - 1 }$.
\begin{enumerate}[label=(\alph*)]
\item Find an expression for the velocity of the particle at time $t$ seconds.
\item Find the time when the particle is travelling in the $\mathbf { i }$ direction.
\item Show that when $t = 4$ the speed of the particle is $20 \mathrm {~ms} ^ { - 1 }$.
\end{enumerate}

\hfill \mbox{\textit{AQA M1 2005 Q7 [8]}}