A uniform rod of mass m and length l suspended by means of two identical inextensible light strings as shown in figure. Tension in one string immediately after the other string is cut, is _ _ _ _ . (g acceleration due to gravity)

Step-by-step solution

When string at B is cut, rod rotates about A. Torque about A: = mg l 2 Moment of inertia about A: I_A = ml^2 3 Angular acceleration: = mg l/2 ml^2/3 = 3g 2l Acceleration of COM: a_ cm = l 2 = 3g 4 Newton's second law: mg - T = ma_ cm T = mg - 3mg 4 = mg 4