question_answer

A stone is attached to one end of a string and rotated in a vertical circle. If string breaks at the position of maximum tension, it will break at

A)  A                                           

B)  B

C)  C                                           

D)  D

Correct Answer: B

Solution :

                The body is describing a vertical circle, \[\therefore \]  \[T-mg\cos \theta =\frac{m{{v}^{2}}}{l}\] or            \[T=mg\cos \theta +\frac{m{{v}^{2}}}{l}\] Tension is maximum when \[\cos \theta =+1\] and velocity is maximum. Both condition are satisfied at \[\theta =0{}^\circ \] (ie, at lowest point B).