For the rotating and oscillating control arm $O A$ of Prob. $7 / 22$, determine the velocity $\mathbf{v}$ and acceleration a of the ball tip $A$ for the condition when $t=1 / 2$ s. Distance $b=120 \mathrm{mm}, s=100 \mathrm{mm},$ and $\theta=\theta_{0} \sin 4 \Omega t$ as defined in Prob. $7 / 22$ with $\Omega=\pi \mathrm{rad} / \mathrm{s}$ and $\theta_{0}=\pi / 6 \mathrm{rad}$