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The rotational inertia of a collapsing spinning star changes to 2/5 its initial value. what is the ratio of the new rotational kinetic energy to the initial rotational kinetic energy (kenew / kei)?

Respuesta :

IssacAsimov
Let K.E[tex] _{i} [/tex] be the intial K.E and K.E[tex] _{new} [/tex] be new K.E,

I[tex] _{new} [/tex] = [tex] \frac{2}{5} I _{i} [/tex]

K.E[tex] _{i} = \frac{I_{i} w^{2} }{2} [/tex] --- (i)
K.E[tex] _{new} = \frac{I_{new}w^{2} }{2} [/tex]

Therefore, 
K.E[tex] _{new} = \frac{2I_{i}w^{2} }{5*2} [/tex] ----(ii)


Dividing i and ii,

[tex] \frac{K.E_{new} }{K.E_{i} } = \frac{2}{5} [/tex]

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