Question

A circular loop of string rotates about its axis on a frictionless horizontal plane at a uniform rate so that the tangential speed of any particle of the string is v. If a small transverse disturbance is produced at a point of the loop, with what speed (relative to the string) will this disturbance travel on the string?

Answer 1

Suppose F is the tension in the string due to its rotation. Choose a small element of the string of length l. If P is the mass per unit length of the string, then mass of the element,

m = µl = µRθ

Using Newton’s second law for the element, we have