(i)[5]
Determine the coefficient of friction between the box and the plane.
(ii)[2]
The force of magnitude $40\,\text{N}$ is taken away. Decide, with a reason, whether the box remains in equilibrium or not.
Mathematics 9709 · AS & A Level · Forces and equilibrium
Forces and equilibrium — practice question
A box of mass $30\,\text{kg}$ is initially at rest on a rough plane inclined at angle $\alpha$ to the horizontal, where $\sin \alpha = 0.1$, and a force of magnitude $40\,\text{N}$ acts on it. This force is directed upwards, parallel to a line of greatest slope of the plane. The box is on the verge of sliding up the plane.
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This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Resolving forces parallel to plane gives: $W\sin\alpha+F=40$” …
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