question_answer

A weight w is suspended from the midpoint of a rope, whose ends are at the same level. In order to make the rope perfectly horizontal, the force applied to each of its ends must be

A)  less than w       

B)  equal to w

C)  equal to 2 w     

D)  infinitely large

Correct Answer: D

Solution :

                 For equilibrium of body                                 mg = 2T \[\cos \theta \] \[\therefore \]  \[T=\frac{mg}{2\cos \theta }\] For the string to be horizontal,                 \[\theta \to {{90}^{o}}\] \[\therefore \]  \[T-\frac{mg}{2\cos {{90}^{o}}}\Rightarrow T\to \infty \]