Mathematics 9709 · AS & A Level · Forces and equilibrium
Forces and equilibrium — practice question
A block B, with mass 15 kg, is held in equilibrium against a horizontal surface between points A and C by forces of magnitudes X N and 40 N. The two forces lie in the same vertical plane, and their directions are shown in the diagram.
(i)[2]
The surface is smooth. Determine the value of $X$.
(ii)[5]
Instead, the surface is rough and the block is in limiting equilibrium. The frictional force on the block has magnitude $10\,\text{N}$ and acts towards $A$. Determine the coefficient of friction between the block and the surface.
Worked solution & mark scheme
This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Horizontal resolution gives $X\cos 30^\circ = 40\cos 60^\circ$” …