Pendulum suspended from Horizontal rotating hoop

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SUMMARY

The discussion focuses on deriving the Lagrangian for a massless hoop rotating horizontally with a pendulum attached. The key equations include the kinetic energy of the hoop, which is zero due to its massless nature, and the kinetic and potential energies of the pendulum. The final expression for the Lagrangian is L = (1/2)M[(L*d∅/dt)² + (R + Lsin∅)²ω²] + MgLcos∅. The user confirms that their calculations appear correct based on the provided equations.

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Homework Statement


A massless hoop is suspended horizontally and is free to rotate about a vertical axis through its center with a constant angular velocity (omega). Attached to the edge of the hoop is a simple pendulum that is restricted to oscillate in only the radial direction. find the Lagrangian of the system.

M= mass of pendulum
L= Length of Pendulum
∅= angle the pendulum makes with the vertical
ω=angular velocity of hoop
R= radius of hoop

Homework Equations



L= T-U
T= Kinetic energy
U=Potential Energy


The Attempt at a Solution


T(hoop)=(1/2) I(hoop)*ω^2
But I is dependent upon the mass of the hoop and since the mass of the hoop is 0 so is I(hoop)->T(hoop)=0

T(pendulum)=(1/2)M[L*(d∅/dt)]^2+(1/2)I(pendulum)*ω^2
T=1/2M[(L*d∅/dt)^2+(R+Lsin∅)^2*ω^2
U=-MgLcos∅

L=(1/2M[(L*d∅/dt)^2+(R+Lsin∅)^2*ω^2)+MgLcos∅

Is this right?
 
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Looks right to me.
 

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