Show Energy Equality of Simple Pendulum with Equipartition

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SUMMARY

The average total energy of a simple pendulum is conclusively shown to be equal to twice the average kinetic energy, as derived from the equation E = T + V = 1/2 ml²(θ'²) + mgl cos(θ). The discussion emphasizes the application of the equipartition theorem, noting that the pendulum must satisfy specific assumptions, particularly regarding thermal equilibrium. It is critical to recognize that variations in potential shape can yield different results, thus not all pendulum-like systems adhere to this conclusion. Explicit calculations of average kinetic energy through integration over one period are necessary for validation.

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  • Knowledge of energy conservation principles
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  • Explore the derivation of average kinetic energy for oscillatory systems
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Homework Statement


How would one show that the average total energy of a simple pendulum is equal to twice the average kinetic energy of the pendulum?

Homework Equations


E = T + V = 1/2 ml**2 (θ'**2) + mgl cos(θ)



The Attempt at a Solution


Maybe use equipartition?
 
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Glenda said:
Maybe use equipartition?
Then you have to show that your pendulum satisfies the assumptions going into that theorem. In particular, your pendulum is not in thermal equilibrium with anything, and a different potential shape will lead to a different result so it does not apply to all pendulum-like systems.

You can explicitly calculate the average kinetic energy by integrating over one period.
 

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