9709 P41 - Jun 2019 - Q4
3623
A particle of mass 1.3 kg rests on a rough plane inclined at an angle \(\theta\) to the horizontal, where \(\tan \theta = \frac{12}{5}\). The coefficient of friction between the particle and the plane is \(\mu\).
(i) A force of magnitude 20 N parallel to a line of greatest slope of the plane is applied to the particle and the particle is on the point of moving up the plane. Show that \(\mu = 1.6\). [4]
The force of magnitude 20 N is now removed.
(ii) Find the acceleration of the particle. [2]
(iii) Find the work done against friction during the first 2 s of motion. [3]
