$CF = M \omega^2 \bar x$
Where:
$M = \rho V = \rho A \pi R$
$x = 2R / \pi$
Thus,
$CF = \rho A \pi R \omega^2 (2R / \pi)$
$CF = 2 \rho A R^2 \omega^2$
$2T = CF$
$2 \sigma A = 2 \rho A R^2 \omega^2$
$\sigma = \rho R^2 \omega^2$
From the given (Note: 1 N = 1 kg·m/sec2):
$\sigma = 150 \, \text{MPa}$
$\sigma = 150\,000\,000 \, \text{kg} \cdot \text{m/sec}^2 \cdot \text{m}^2$
$\sigma = 150\,000\,000 \, \text{kg/m} \cdot \text{sec}^2$
$\rho = 7.85 \, \text{Mg/m}^3 = 7850 \, \text{kg/m}^3$
$R = 220 \, \text{mm} = 0.22 \, \text{m}$
Therefore,
$150\,000\,000 = 7850(0.22)^2 \, \omega^2$
$\omega = 628.33 \, \text{rad/sec}$ answer