question_answer

A stone is tied up to the end of a string and whirled in a vertical circle. The tension of the string is T1 when the stone is at the highest point and T2 ,when it is at the lowest point, then:

A) \[{{T}_{1}}<2{{T}_{2}}\]                                

B)  \[{{T}_{1}}={{T}_{2}}\]

C) \[{{T}_{1}}>{{T}_{2}}\]                                  

D)  \[{{T}_{1}}<{{T}_{2}}\]

Correct Answer: D

Solution :

                 At the lowest point A the tension in the string is \[{{T}_{1}}=\frac{mv_{1}^{2}}{r}+mg\]                                   ?(i) At the highest point B the tension in the string is \[{{T}_{2}}=\frac{m{{v}^{2}}}{r}-mg\]                                                     ?(ii) Therefore, it is quite clear that the tension at the highest point on the circle, is less than that of the tension at the lowest point.