A uniform rod $AB$ weighs $15\,\text{N}$ and measures $1.2\,\text{m}$ in length. The end $A$ of the rod is touching a rough plane that is inclined at $30^\circ$ to the horizontal, with the rod at right angles to the plane. The rod is maintained in equilibrium in this arrangement by a horizontal force acting at $B$, in the vertical plane that contains the rod (see diagram).
(i)[3]
Show that the size of the force applied at $B$ is $4.33\,\text{N}$, correct to 3 significant figures.
(ii)[2]
Determine the size of the frictional force exerted by the plane on the rod.
(iii)[3]
Because the rod is in limiting equilibrium, calculate the coefficient of friction between the rod and the plane.
Worked solution & mark scheme
This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Moments are taken about $A$” …