A potter's wheel moves from rest to an angular speed of $0\mathrm{.}50re\frac{v}{s}$ in $31\mathrm{.}7s.$

Assuming constant angular acceleration, what is its angular acceleration in $ra\frac{d}{s^2}?$

Answer in units of $ra\frac{d}{s^2}.$ Answer in units of $ra\frac{d}{s^2}.$