7 Two forces, which act in a vertical plane, are applied to a crate. The crate has mass 50 kg , and is initially at rest on a rough horizontal surface. One force has magnitude 80 N and acts at an angle of \(30 ^ { \circ }\) to the horizontal and the other has magnitude 40 N and acts at an angle of \(20 ^ { \circ }\) to the horizontal. The forces are shown in the diagram.
\includegraphics[max width=\textwidth, alt={}, center]{01338c87-302c-420f-a473-39b0796ccaed-16_241_999_493_523}
The coefficient of friction between the crate and the surface is 0.6 .
Model the crate as a particle.
- Draw a diagram to show the forces acting on the crate.
- Find the magnitude of the normal reaction force acting on the crate.
- Does the crate start to move when the two forces are applied to the crate? Show all your working.
- State one aspect of the possible motion of the crate that is ignored by modelling it as a particle.
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