Edexcel M2 2013 June — Question 5

Exam BoardEdexcel
ModuleM2 (Mechanics 2)
Year2013
SessionJune
TopicMoments

5. \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{cf960066-46b8-42a3-8a8b-d8deb76e7c70-09_522_997_276_477} \captionsetup{labelformat=empty} \caption{Figure 3}
\end{figure} A uniform rod \(A B\), of mass \(m\) and length \(2 a\), is freely hinged to a fixed point \(A\). A particle of mass \(m\) is attached to the rod at \(B\). The rod is held in equilibrium at an angle \(\theta\) to the horizontal by a force of magnitude \(F\) acting at the point \(C\) on the rod, where \(A C = b\), as shown in Figure 3. The force at \(C\) acts at right angles to \(A B\) and in the vertical plane containing \(A B\).
  1. Show that \(F = \frac { 3 a m g \cos \theta } { b }\).
  2. Find, in terms of \(a , b , g , m\) and \(\theta\),
    1. the horizontal component of the force acting on the rod at \(A\),
    2. the vertical component of the force acting on the rod at \(A\). Given that the force acting on the rod at \(A\) acts along the rod,
  3. find the value of \(\frac { a } { b }\).