Rotational Kinematics & Dynamics question from NEET 2000 (AIPMT)

Answer: (b)

1. In a vertical circle $T = \dfrac{mv^2}{r} + mg\cos\theta$ (θ measured from the lowest point).
2. At the lowest point B the speed is maximum and gravity also acts away from the centre, so tension is maximum there.
3. So the string breaks first at B: answer (b).