Rigid body rotation. Need explanation

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SUMMARY

The discussion centers on the concept of rigid body rotation, specifically the relationship between linear velocity (V), radius (r), and angular velocity (W) as described by the equation V = rW. The user struggles with deriving the correct relationship between the velocities at different radii, ultimately seeking clarification on angular momentum. The correct relationship is established as Vc/rc = Vf/rf, indicating that angular velocities differ based on the radius of rotation. The user is advised to understand the distinction between angular velocity and angular momentum for a complete grasp of the topic.

PREREQUISITES
  • Understanding of rigid body dynamics
  • Familiarity with angular velocity (W) and linear velocity (V)
  • Knowledge of angular momentum concepts
  • Basic algebra skills for manipulating equations
NEXT STEPS
  • Study the principles of angular momentum in rigid body motion
  • Learn about the conservation of angular momentum
  • Explore the relationship between linear and angular velocity in various contexts
  • Review examples of rigid body rotation problems and solutions
USEFUL FOR

Students studying physics, particularly those focusing on mechanics and rigid body dynamics, as well as educators seeking to clarify concepts of angular velocity and momentum.

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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