question_answer

A weight \[mg\] is suspended from the middle of a rope whose ends are at same level. If the rope is no longer horizontal, the minimum tension required to completely straighten the rope will be

A) \[mg\]                                 

B) \[\sqrt{mg}\]

C)   Infinite                              

D)   zero

Correct Answer: C

Solution :

The given situation can be shown as from figure    \[2T\sin \theta =mg\] or            \[T=\frac{mg}{2\sin \theta }\] when rope is straight,\[\theta ={{0}^{o}}\] \[\therefore \]  \[T=\frac{mg}{2\sin 0}=\infty \]                 (infinite)