9709 P42 - Nov 2015 - Q6
4090
A small ring of mass 0.024 kg is threaded on a fixed rough horizontal rod. A light inextensible string is attached to the ring and the string is pulled with a force of magnitude 0.195 N at an angle of \(\theta\) with the horizontal, where \(\sin \theta = \frac{5}{13}\). When the angle \(\theta\) is below the horizontal (see Fig. 1) the ring is in limiting equilibrium.
(i) Find the coefficient of friction between the ring and the rod.
When the angle \(\theta\) is above the horizontal (see Fig. 2) the ring moves.
(ii) Find the acceleration of the ring.
