Q. A small object of mass $m$ is attached to a light string which passes through a hollow tube. The tube is hold by one hand and the string by the other. The object is set into rotation in a circle of radius $R$ and velocity $v$. The string is then pulled down, shortening the radius of path of $r$. What is conserved
A) Angular momentum
B) Linear momentum
C) Kinetic energy
D) None of the above
Explanation
(a) In the absence of external torque angular momentum remains constant
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.