Proving Rotational K.E. Formula?

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SUMMARY

The total kinetic energy of a free, rigid body can be expressed with the formula E_k = \frac{1}{2}\left(M_{T} v_{c}^{2} + I_{c} ω^{2}\right), where M_T represents the total mass and I_c denotes the moment of inertia. To prove this formula for a rotating body, one must integrate the expression ##\int \frac{1}{2}v^2 \rho dV##, which accounts for the kinetic energy of all infinitesimal mass components. By separating the velocity into translational and rotational components, the derivation leads to the established kinetic energy formula.

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The total kinetic energy (as viewed from one inertial frame) of a free, rigid body is the sum of all the infinitesimal kinetic energies of the components that comprise the body.


How do we prove that for a rotating body

E_k=\frac{1}{2}\left(M_{T} v_{c}^{2} + I_{c} ω^{2}\right)
 
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Where MT stands for the total mass of all the infinitesmal components combined.
 
Integrate ##\int \frac{1}{2}v^2 \rho dV## (in other words, kinetic energy = 1/2m^2 for all infinitesimal m) and split v into components from translation and rotation and you will get the correct result.
 

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