Q. The minimum speed for a particle at the lowest point of a vertical circle of radius $r$, to describe the circle is $v$. If the radius of the circle is reduced to one-fourth its value, the corresponding minimum speed will be
A) $v/4$
B) $v/2$
C) 2$v$
D) 4$v$
Explanation
(b) $v = \sqrt{5gR}$
When $R^{'} = \frac{R}{4}$
$v^{'} = \sqrt{5gR'} = \sqrt{5gR/4} = \frac{1}{2}\sqrt{5gR} = \frac{1}{2}v$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.