A) \[\sqrt{3gr}\]
B) \[\sqrt{2gr}\]
C) \[\sqrt{gr}\]
D) \[\sqrt{gr/2}\]
Correct Answer: C
Solution :
When a body tied to the end of a string is revolved in a vertical circle, the speed of the body is different at different points of the circular paths. The resultant of tension\[(T)\]and weight\[(mg)\]provider the necessary centripetal force \[ie,\] \[T+mg=\frac{mv_{A}^{2}}{r}\] Tension\[(T)\]becomes zero at the points of minimum velocity, therefore \[\therefore \] \[0+mg=\frac{mv_{A}^{2}}{r}\] \[\Rightarrow \] \[{{v}_{A}}=\sqrt{gr}\]You need to login to perform this action.
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