Tricky Mechanics

  • #1

Homework Statement



See attached figure. Derive the equation of motion for the following in the parameter [tex]\theta[/tex]

Homework Equations





The Attempt at a Solution



The only part thats giving me trouble is the uppermost massive bar connecting the spring to the mass. I am trying to write down its kinetic energy. I know this can be decomposed as

[tex]
T = \frac{1}{2}m\bar{v}^2 + \frac{1}{2}I_{CM}\omega^2
[/tex]

where v-bar is the center of mass velocity and omega is the angular velocity of the body about its CM. I can get the first term, but I can't begin to figure out how to get Omega in the second term. I thought about considering a small change in the position of the mass, as this of course gives rise to a rotation of this bar, but the CM moves during this and it throws me off. Suggestions on how to get Omega, or on an alternative approach would be appreciated.
 

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Answers and Replies

  • #2
Hmmm, after another attempt I still can't make heads or tails of finding Omega
 
  • #3
tiny-tim
Science Advisor
Homework Helper
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Hi John! :smile:
Hmmm, after another attempt I still can't make heads or tails of finding Omega
?? :confused: ω = dθ/dt :wink:
 

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