The system shown in the fig. is in equilibrium. Pulleys A and B have mass M each and the block C has mass 2M. The strings are light. There is an insect (D) of mass M/2 sitting at the middle or the right string. Insect does not move.

(a) Just by inspection, say if the tension in the string S1 is equal to, more than or less than 9/2 Mg.
(b) Find tension in the string S2, and S1.
(c) Find tension in S2 if the insect flies and sits at point E on the string.

Answer

(a) More than 9/2 Mg
(b) Tension in S2 = Mg/2 , Tension is S1 = 5 Mg
(c) Tension in S2 = Mg/7