JEE Main & Advanced
Physics
Two Dimensional Motion
Question Bank
Non-uniform Circular Motion
question_answer
A block of mass \[m\] at the end of a string is whirled round in a vertical circle of radius \[R\]. The critical speed of the block at the top of its swing below which the string would slacken before the block reaches the top is [DCE 1999, 2001]
A) \[Rg\]
B) \[{{(Rg)}^{2}}\]
C) \[R/g\]
D) \[\sqrt{Rg}\]
Correct Answer:
D
Solution :
At highest point \[\frac{m{{v}^{2}}}{R}=mg\] Þ \[v=\sqrt{gR}\]