A particle is in uniform circular motion, then its velocity is perpendicular to

A particle is revolving in a circular path of radius $2 \mathrm{m}$ with constant angular speed $4 \mathrm{rad} {\mathrm{s}}^{-1}.$ The angular acceleration of particle is

Two particles each of mass $m$ are moving in horizontal circle with same angular speed. If both string are of same length then the ratio of tension in string $\frac{T_1}{T_2}$ is