19. Let \( R \) be the region enclosed by the graph of \( y = 3\sqrt{x} - x \) and the x-axis. The region \( R \) models the surface of a small pond. At all points in \( R \) at a distance \( x \) from the y-axis, the depth of the water is given by \( g(x) = \frac{1}{\sqrt{x}} \). What is the volume of the water in the pond?
