Answer
$v_r=ae^{at}$
$v_\theta=e^{at}$
$a_r=e^{at}(a^2-1)$
$a_\theta=2ae^{at}$
Work Step by Step
$r=e^{at}$
$\dot{r}=ae^{at}$
$\ddot{r}=a^2e^{at}$
$\theta=t$
$\dot{\theta}=1$
$\ddot{\theta}=0$
$v_r=\dot{r}=ae^{at}$
$v_\theta=r\dot{\theta}=e^{at}$
$a_r=\ddot{r}-r\dot{\theta}^2=a^2e^{at}-e^{at}(1)^2=e^{at}(a^2-1)$
$a_\theta=r\ddot{\theta}+2\dot{r}\dot{\theta}=e^{at}(0)+2(ae^{at})(1)=2ae^{at}$