Q. A stone is tied at one end of a 5m long string and whirled in a vertical circle. The minimum speed required to just cross the topmost position is
A) 5 $ms^{- 1}$
B) 7 $ms^{- 1}$
C) 57 $ms^{- 1}$
D) 75 $ms^{- 1}$
Explanation
(b) $v = \sqrt{gr} = \sqrt{9.8 \times 5} = 7\ ms^{- 1}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.