OCR MEI Paper 1 2018 June — Question 11

Exam BoardOCR MEI
ModulePaper 1 (Paper 1)
Year2018
SessionJune
TopicMotion on a slope

11 Fig. 11 shows two blocks at rest, connected by a light inextensible string which passes over a smooth pulley. Block A of mass 4.7 kg rests on a smooth plane inclined at \(60 ^ { \circ }\) to the horizontal. Block B of mass 4 kg rests on a rough plane inclined at \(25 ^ { \circ }\) to the horizontal. On either side of the pulley, the string is parallel to a line of greatest slope of the plane. Block B is on the point of sliding up the plane. \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{904025c9-6d68-4344-bd41-8c0fccfcf92f-07_332_931_443_575} \captionsetup{labelformat=empty} \caption{Fig. 11}
\end{figure}
  1. Show that the tension in the string is 39.9 N correct to 3 significant figures.
  2. Find the coefficient of friction between the rough plane and Block B.