Rigid body rotation. Need explanation

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Homework Help Overview

The discussion revolves around the topic of rigid body rotation, specifically focusing on the relationship between linear and angular velocities as expressed in the equation V = rW. Participants are examining a problem related to this concept, where discrepancies arise between their calculations and the expected results from a textbook.

Discussion Character

  • Mixed

Approaches and Questions Raised

  • The original poster attempts to apply the formula V = rW and manipulate it algebraically to derive a relationship between different velocities and radii. Some participants question the correctness of the original poster's calculations, while others suggest clarifying the definitions of angular velocity and angular momentum.

Discussion Status

The discussion is ongoing, with participants providing feedback on the original poster's work. Some guidance has been offered regarding the distinction between angular velocities in different contexts, but there is no explicit consensus on the resolution of the problem.

Contextual Notes

There appears to be confusion regarding the application of the formula and the assumptions about angular velocity in different scenarios. The original poster's calculations lead to a result that contradicts the textbook answer, prompting further exploration of the underlying concepts.

am_knightmare
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Homework Statement



https://dl.dropbox.com/u/66988308/Capture.JPG

Homework Equations


V=rW

The Attempt at a Solution


I tried to plug in the formula , and algebras but I keep getting rc/rf as answer instead of rf/rc as the book says.
Work:
Vf=(rf)W
W=Vf/rf
W=Vc/rc

Vc/rc = Vf/rf
(Vc)(rf) = (Vf) (rc)
(Vc)(rf) / (Vf) (rc)= 1
Im not sure if this is the right track.
Thanks for any advice.
 
Last edited by a moderator:
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Please show your working.
 
The book is correct.
 
My work is shown in first post now.
 
"W" (ω), angular velocity, is not the same in each case.
 
Do you know what angular momentum is?
 

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