A water barrel stands on a table of height h. If a small hole is punched in the side of the barrel at its base, it is found that the resultant stream of water strikes the ground at a horizontal distance R from the table. What is the depth of water in the barrel?
(1) $\frac{R^2}{h}$                       (2) $\frac{R^2}{2h}$                (3) $\frac{R^2}{4h}$              (4) $\frac{4R^2}{h}$