Edexcel M2 2007 January — Question 5

Exam BoardEdexcel
ModuleM2 (Mechanics 2)
Year2007
SessionJanuary
TopicMoments

5. \begin{figure}[h]
\captionsetup{labelformat=empty} \caption{Figure 2} \includegraphics[alt={},max width=\textwidth]{7ae16b00-d388-4c1b-a195-c785a3900548-07_551_636_306_660}
\end{figure} A horizontal uniform \(\operatorname { rod } A B\) has mass \(m\) and length \(4 a\). The end \(A\) rests against a rough vertical wall. A particle of mass \(2 m\) is attached to the rod at the point \(C\), where \(A C = 3 a\). One end of a light inextensible string \(B D\) is attached to the rod at \(B\) and the other end is attached to the wall at a point \(D\), where \(D\) is vertically above \(A\). The rod is in equilibrium in a vertical plane perpendicular to the wall. The string is inclined at an angle \(\theta\) to the horizontal, where \(\tan \theta = \frac { 3 } { 4 }\), as shown in Figure 2.
  1. Find the tension in the string.
  2. Show that the horizontal component of the force exerted by the wall on the rod has magnitude \(\frac { 8 } { 3 } m g\). The coefficient of friction between the wall and the rod is \(\mu\). Given that the rod is in limiting equilibrium,
  3. find the value of \(\mu\). \includegraphics[max width=\textwidth, alt={}, center]{7ae16b00-d388-4c1b-a195-c785a3900548-08_158_136_2595_1822}