| Exam Board | Pre-U |
|---|---|
| Module | Pre-U 9794/3 (Pre-U Mathematics Paper 3) |
| Year | 2013 |
| Session | November |
| Marks | 5 |
| Topic | Moments |
| Type | Particle suspended by strings |
| Difficulty | Standard +0.3 This is a straightforward statics problem requiring resolution of forces in equilibrium. Part (i) involves basic trigonometry and force resolution with perpendicular strings (Pythagoras or components), while part (ii) tests conceptual understanding of vertical equilibrium. Standard mechanics question with clear setup and routine methods, slightly easier than average A-level. |
| Spec | 3.03m Equilibrium: sum of resolved forces = 03.03n Equilibrium in 2D: particle under forces |
A parcel $P$ of weight 50 N is being held in equilibrium by two light, inextensible strings $AP$ and $BP$. The string $AP$ is attached to a wall at $A$, and string $BP$ passes over a smooth pulley which is at the same height as $A$, as shown in the diagram. When the tension in $BP$ is 40 N, the strings are at right angles to each other.
\includegraphics{figure_10}
\begin{enumerate}[label=(\roman*)]
\item Find the tension in string $AP$. [4]
\item Explain why the parcel can never be in equilibrium with both strings horizontal. [1]
\end{enumerate}
\hfill \mbox{\textit{Pre-U Pre-U 9794/3 2013 Q10 [5]}}