# transformation of rotating object

by Jakedasnake
Tags: object, rotating, transformation
 P: 1 If a disc-like object was rotating so that its outside edge was at about 0.86c (causing a factor of change of about 2) relative to an observer, then would it contract in length along the axis of rotation, or the circumference (relative to the observer)? in other words, would it get thinner or smaller? Please correct me on any mistakes I made because I have next to no knowledge on this subject, I just need this information for a thought experiment I've been working on.
 P: 937 Why do you think the wheel would contract at all?
P: 3,543
 Quote by Jakedasnake If a disc-like object was rotating so that its outside edge was at about 0.86c (causing a factor of change of about 2) relative to an observer, then would it contract in length along the axis of rotation, or the circumference (relative to the observer)? in other words, would it get thinner or smaller? Please correct me on any mistakes I made because I have next to no knowledge on this subject, I just need this information for a thought experiment I've been working on.
See: http://en.wikipedia.org/wiki/Ehrenfest_paradox

Spinning up a rigid disc from rest would brake it. For a deformable disc I'm not sure if radial contraction is possible due to centrifugal forces. It might depend on the assumed theoretical material properties. Real world materials would break way below this speeds.

But you can build an already spinning disc from rigid elements. The geometry described by those rigid elements is non-Euclidean.

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