How much fraction of the kinetic energy of rolling is purely:
  1. Translational.
  2. Rotational.
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  1. Fraction of translational kinetic energy
$=\frac{\frac{1}{2}\text{mv}^2}{\frac{1}{2}\text{mv}^2+\frac{1}{2}\text{I}\omega^2}=\frac{1}{1+\frac{\text{k}^2}{\text{r}^2}}$
$=\frac{\text{r}^2}{(\text{k}^2+\text{r}^2)}$
  1. Fraction of rotational kinetic energy
$=\frac{\frac{1}{2}\text{I}\omega^2}{\frac{1}{2}\text{mv}^2+\frac{1}{2}\text{I}\omega^2}=\frac{\frac{\text{k}^2}{\text{r}^2}}{1+\frac{\text{k}^2}{\text{r}^2}}$
$=\frac{\text{r}^2}{(\text{r}^2+\text{k}^2)}$
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