grindstone, initially at rest, is given a constant angular acceleration so that it makes

$20\mathrm{.}0$ rev in the first $8\mathrm{.}00$ s$.$ What is its angular acceleration?

A$)0\mathrm{.}313$ rad$/$s$2$

B$)0\mathrm{.}625$ rad$/$s$2$

C$)2\mathrm{.}50$ rad$/$s$2$

D$)1\mathrm{.}97$ rad$/$s$2$

E$)3\mathrm{.}93$ rad$/$s