A body moving in a circle, with radius R, with angular velocity $\displaystyle \omega$ can be represented by the parametric equations $\displaystyle x= R cos(\omega t)$, $\displaystyle y= R sin(\omega t)$. Differentiating, the velocity vector is given by $\displaystyle v_x= -\omega R sin(\omega t)$, $\displaystyle v_y= \omega R cos(\omega t)$. Differentiating again, the accelertation is given by $\displaystyle a_x= -\omega^2R R cos(\omega)$, $\displaystyle v_y= -\omega^2 R sin(\omega t)$. And, of course, ma= F which you have from part a.