| Exam Board | Edexcel |
|---|---|
| Module | M2 (Mechanics 2) |
| Year | 2018 |
| Session | January |
| Marks | 6 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Impulse and momentum (advanced) |
| Type | Energy change from impulse |
| Difficulty | Standard +0.3 This is a straightforward multi-step mechanics problem requiring impulse-momentum theorem to find final velocity, then calculating kinetic energies before and after. The vector arithmetic is simple, and the method is standard textbook procedure with no conceptual subtlety—slightly easier than average due to its routine nature. |
| Spec | 6.02d Mechanical energy: KE and PE concepts6.03f Impulse-momentum: relation |
| Answer | Marks | Guidance |
|---|---|---|
| Answer/Working | Mark | Guidance |
| Impulse-momentum equation | M1 | Must be subtracting velocities (or equivalent). Dimensionally correct. |
| \(4\mathbf{i} + 5\mathbf{j} = \frac{1}{2}(\mathbf{v} - (2\mathbf{i} - 3\mathbf{j}))\) | A1 | Correct unsimplified equation |
| \(\mathbf{v} = 10\mathbf{i} + 7\mathbf{j}\) | A1 | Seen or implied |
| KE Gain | M1 | Dimensionally correct. Condone \(\pm\). Must be difference of two KE terms. |
| \(= \frac{1}{2}0.5(10^2 + 7^2 - (2^2 + (-3)^2))\) | A1ft | Correct unsimplified expression. Follow their \(\mathbf{v}\). Condone \(\pm\) |
| \(= 34\) J | A1 | CSO |
## Question 1:
| Answer/Working | Mark | Guidance |
|---|---|---|
| Impulse-momentum equation | M1 | Must be subtracting velocities (or equivalent). Dimensionally correct. |
| $4\mathbf{i} + 5\mathbf{j} = \frac{1}{2}(\mathbf{v} - (2\mathbf{i} - 3\mathbf{j}))$ | A1 | Correct unsimplified equation |
| $\mathbf{v} = 10\mathbf{i} + 7\mathbf{j}$ | A1 | Seen or implied |
| KE Gain | M1 | Dimensionally correct. Condone $\pm$. Must be difference of two KE terms. |
| $= \frac{1}{2}0.5(10^2 + 7^2 - (2^2 + (-3)^2))$ | A1ft | Correct unsimplified expression. Follow their $\mathbf{v}$. Condone $\pm$ |
| $= 34$ J | A1 | CSO |
---\begin{enumerate}
\item A ball of mass 0.5 kg is moving with velocity $( 2 \mathbf { i } - 3 \mathbf { j } ) \mathrm { m } \mathrm { s } ^ { - 1 }$ when it receives an impulse $( 4 \mathbf { i } + 5 \mathbf { j } ) \mathrm { Ns }$. Find the gain in kinetic energy of the ball due to the impulse.\\
(6)\\
\end{enumerate}
\hfill \mbox{\textit{Edexcel M2 2018 Q1 [6]}}