A simple pendulum of length t and mass m is initially at its lowest position. It is given the minimum horizontal speed necessary to move in a circular path about the point of suspension. The tension in the string at the lowest position of the bob is-
A)3mg
B)4mg
C)5 mg
D)6 mg
Correct Answer:
D
Solution :
To complete the circle \[{{v}_{\min }}=\sqrt{5g\ell }\] \[T-mg=\frac{m{{v}^{2}}}{\ell };\] \[T\,\,-\,\,mg\,\,=\,\,5\,mg\] \[T\,\,=\,\,6\,mg\]