7
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A small ring of mass 0.2 kg is threaded on a fixed vertical rod. The end \(A\) of a light inextensible string is attached to the ring. The other end \(C\) of the string is attached to a fixed point of the rod above \(A\). A horizontal force of magnitude 8 N is applied to the point \(B\) of the string, where \(A B = 1.5 \mathrm {~m}\) and \(B C = 2 \mathrm {~m}\). The system is in equilibrium with the string taut and \(A B\) at right angles to \(B C\) (see diagram).
- Find the tension in the part \(A B\) of the string and the tension in the part \(B C\) of the string.
The equilibrium is limiting with the ring on the point of sliding up the rod.
- Find the coefficient of friction between the ring and the rod.