A hemisphere is placed so that its flat face is in contact with a table. It has radius $r$ and density $\rho$. The volume of a sphere is $\frac{4}{3}\pi r^3$. What is the mean pressure the object exerts on the table?
- A$\frac{1}{3}\rho r^2$
- B$\frac{1}{3}\rho r^2 g$
- C$\frac{2}{3}\rho r$
- D$\frac{2}{3}\rho r g$