Q. A man is supported on a frictionless horizontal surface. It is attached to a string and rotates about a fixed centre at an angular velocity $\omega$. The tension in the string if $F$. If the length of string and angular velocity are doubled, the tension is string is now
A) $F$
B) $F/2$
C) $4\ F$
D) $8\ F$
Explanation
(d) Tension is string = centrifugal force
In first case, $F = m\ r\ \omega^{2}$
In second case, $F^{'} = m(2r)(2\omega)^{2} = 8mr{\ \omega}^{2} = 8\ F$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.