Mathematics 9709 · AS & A Level · Forces and equilibrium
Forces and equilibrium — practice question
A particle with mass $1.3\,\text{kg}$ is at rest on a rough plane inclined at angle $\theta$ to the horizontal, where $\tan\theta = \frac{12}{5}$. The coefficient of friction between the particle and the plane is $\mu$.
(i)[4]
A force of magnitude $20\,\text{N}$ acting parallel to a line of greatest slope of the plane is applied to the particle, which is on the point of moving up the plane. Show that $\mu = 1.6$.
(ii)[2]
The $20\,\text{N}$ force is now taken away. Determine the acceleration of the particle.
(iii)[3]
Determine the work done against friction in the initial $2\,\text{s}$ of motion.
Worked solution & mark scheme
This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Perpendicular to the plane gives: $R=13\cos67.4=5$” …