Consider a solid sphere of radius R and mass density \(\rho(\mathrm{r})=\rho_0\left(1-\frac{\mathrm{r}^2}{\mathrm{R}^2}\right)\). 0 < r ≤ R. The minimum density of a liquid in which it will float is:
1
\(\frac{\rho_0}{5}\)
2
\(\frac{\rho_0}{3}\)
3
\(\frac{2 \rho_0}{5}\)
4
\(\frac{2 \rho_0}{3}\)