question_answer

A sphere of mass m is tied to end of a string of length\[l\]and rotated through the other end along a horizontal circular path with speed v. The work done in full horizontal circle is

A)  zero                                     

B)  \[\left( \frac{m{{v}^{2}}}{l} \right)2\pi l\]

C)  \[mg.\,2\pi l\]                  

D)         \[\left( \frac{m{{v}^{2}}}{l} \right)(l)\]