Q. A body of mass 1 kg is rotating in a vertical circle of radius 1m. What will be the difference in its kinetic energy at the top and bottom of the circle? (Take $g = 10\ ms^{- 2}$)

A) 10 J
B) 20 J
C) 30 J
D) 50 J
Explanation

(b) Difference in $KE = \frac{1}{2}m\left\lbrack \left( \sqrt{5gr} \right)^{2} - \sqrt{gr} \right\rbrack^{2}$
$= 2mgr = 2 \times 1 \times 10 \times 1 = 20\ $J

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.