Action Var: 1 DOF System, Ellipse Path in Phase-Space

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The discussion centers on the action variable J for a 1 degree of freedom system, specifically in the context of a harmonic oscillator. The action variable is defined by the integral J≡∮ p(q)dq, where the integral is taken over a period of p(q). The challenge arises due to the elliptical path in phase-space, which complicates the determination of the period for integration. Participants emphasize the importance of parametrizing the ellipse correctly to facilitate the integration process.

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Suppose a 1 degree of freedom system. Then, the action variable J is defined by

[tex]J\equiv\oint p(q)dq[/tex]

where the integral is taken over a period of p(q). What shall this period be in the case of say, an harmonic oscillator, where the path in phase-space is an ellipse and hence p(q) is not even single-valued?
 
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quasar987 said:
Suppose a 1 degree of freedom system. Then, the action variable J is defined by

[tex]J\equiv\oint p(q)dq[/tex]

where the integral is taken over a period of p(q). What shall this period be in the case of say, an harmonic oscillator, where the path in phase-space is an ellipse and hence p(q) is not even single-valued?

Parametrize the ellipse in the standard way, and integrate over one period.
 
Dang it. This is what I tought about doing in my exam too but I had no more time when the idea finally hit me. Thanks GJ.
 

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