4 Fig. 4 shows a non-uniform rigid plank AB of weight 900 N and length 2.5 m . The centre of mass of the plank is at G which is 2 m from A . The end A rests on rough horizontal ground and does not slip. The plank is held in equilibrium at \(20 ^ { \circ }\) above the horizontal by a force of \(T \mathrm {~N}\) applied at B at an angle of \(55 ^ { \circ }\) above the horizontal as shown in Fig. 4.
\begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{54711a46-83ce-4fb9-b6d3-53b264725c74-3_426_672_539_605}
\captionsetup{labelformat=empty}
\caption{Fig. 4}
\end{figure}
- Show that \(T = 700\) (correct to 3 significant figures).
- Determine the possible values of the coefficient of friction between the plank and the ground.