# Showing function is in sobolev space

I am trying to show that the function $u(r,\theta)=r^{2/3} sin((2\theta+\pi)/3)$ defined on the domain $0 \le r \le 1$ and $- \pi /2 \le \theta \le \pi$ is in $H^1(\Omega)$ but not in $H^2(\Omega)$.