# Tension in wire rotating with a drum [closed]

A wire of length $L$ and mass $M$ is fastened around a circular drum and the drum is set into rotation about its centre with constant angular velocity $\omega$. I wanted to find the tension in the string. (Question taken up from Kleppner and Kolenkow Mechanics).

Here is a solutions to this question with a diagram of the $\triangle \theta$ portion of the curve. One thing that baffles me here is why the normal reaction on the wire has not been taken into account. Because then the equations would become

$$T \triangle \theta - \triangle N= \triangle m r {\omega}^ 2$$

## closed as off-topic by John Rennie, Jon Custer, user36790, Gert, JamalSOct 22 '16 at 9:31

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• I agree with you. The problem should have stated that the wire is pre-loaded in tension when it is initially placed on the drum. Then the problem statement would have made sense (at least to me). – Chet Miller Oct 21 '16 at 20:49