| Exam Board | WJEC |
|---|---|
| Module | Unit 2 (Unit 2) |
| Session | Specimen |
| Marks | 7 |
| Paper | Download PDF ↗ |
| Mark scheme | Download PDF ↗ |
| Topic | Pulley systems |
| Type | Two particles over pulley, vertical strings |
| Difficulty | Moderate -0.8 This is a standard Atwood machine problem requiring Newton's second law applied to a two-body system. Part (a) involves routine setup of two equations (one for each mass) and simultaneous solving for acceleration and tension—a textbook exercise with no novel insight required. Part (b) tests basic understanding of modeling assumptions. The 6+1 mark allocation and straightforward method make this easier than average for A-level mechanics. |
| Spec | 3.03k Connected particles: pulleys and equilibrium3.03l Newton's third law: extend to situations requiring force resolution |
The diagram below shows two particles $A$ and $B$, of mass 2 kg and 5 kg respectively, which are connected by a light inextensible string passing over a fixed smooth pulley. Initially, $B$ is held at rest with the string just taut. It is then released.
\includegraphics{figure_4}
\begin{enumerate}[label=(\alph*)]
\item Calculate the magnitude of the acceleration of $A$ and the tension in the string. [6]
\item What assumption does the word 'light' in the description of the string enable you to make in your solution? [1]
\end{enumerate}
\hfill \mbox{\textit{WJEC Unit 2 Q7 [7]}}