13-P5. The ring has a mass of 0.5 kg and is resting on the surface of the table. In an effort to move the ring a normal force P from

the finger is exerted on it. If this force is directed towards the ring's center O as shown, determine its magnitude when the ring is on the verge of slipping at A. The coefficient of static friction at A is µA = 0.2 and at B, uB =0.3.