Edexcel M2 — Question 1 6 marks

Exam BoardEdexcel
ModuleM2 (Mechanics 2)
Marks6
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TopicMomentum and Collisions
TypeVector impulse: find velocity or speed after impulse
DifficultyModerate -0.3 This is a straightforward application of the impulse-momentum theorem (Impulse = change in momentum) with vector components. Students need to set up two equations from the i and j components and solve simultaneously. While it requires careful algebraic manipulation, it's a standard M2 exercise with no conceptual challenges beyond direct formula application.
Spec6.03f Impulse-momentum: relation6.03g Impulse in 2D: vector form

A ball, of mass \(m\) kg, is moving with velocity \((5\mathbf{i} - 3\mathbf{j})\) ms\(^{-1}\) when it receives an impulse of \((-2\mathbf{i} - 4\mathbf{j})\) Ns. Immediately after the impulse is applied, the ball has velocity \((3\mathbf{i} + k\mathbf{j})\) ms\(^{-1}\). Find the values of the constants \(k\) and \(m\). [6 marks]

AnswerMarks Guidance
\(m(5i - 3j) - 2i - 4j = m(3i + kj)\)M1 A1 M1 A1
\(-3m - 4 = km\)M1 A1
\(5m - 2 = 3m\) → \(m = 1\)
\(k = -7\) Total: 6 marks
$m(5i - 3j) - 2i - 4j = m(3i + kj)$ | M1 A1 M1 A1 |
$-3m - 4 = km$ | M1 A1 |
$5m - 2 = 3m$ → $m = 1$ | |
$k = -7$ | | **Total: 6 marks**
A ball, of mass $m$ kg, is moving with velocity $(5\mathbf{i} - 3\mathbf{j})$ ms$^{-1}$ when it receives an impulse of $(-2\mathbf{i} - 4\mathbf{j})$ Ns. Immediately after the impulse is applied, the ball has velocity $(3\mathbf{i} + k\mathbf{j})$ ms$^{-1}$.

Find the values of the constants $k$ and $m$. [6 marks]

\hfill \mbox{\textit{Edexcel M2  Q1 [6]}}