7.
\begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{b896c631-00a0-46c5-bce9-16d65f6e3095-13_364_833_269_561}
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\caption{Figure 4}
\end{figure}
A particle \(P\) of mass 2.7 kg lies on a rough plane inclined at \(40 ^ { \circ }\) to the horizontal. The particle is held in equilibrium by a force of magnitude 15 N acting at an angle of \(50 ^ { \circ }\) to the plane, as shown in Figure 4. The force acts in a vertical plane containing a line of greatest slope of the plane. The particle is in equilibrium and is on the point of sliding down the plane.
Find
- the magnitude of the normal reaction of the plane on \(P\),
- the coefficient of friction between \(P\) and the plane.
The force of magnitude 15 N is removed.
- Determine whether \(P\) moves, justifying your answer.