Drainage of a Hemispherical Tank
A full hemispherical tank of radius drains under the influence of gravity from a circular hole of radius at the bottom of the tank. The velocity of fluid flowing from the hole is (Torricelli's law), where is the gravitational acceleration and is the height of water at time , which is shown in the tank and plotted below.
The differential equation for the depth of fluid at time is
Integrating and finding the constant yields
The time that it takes for the tank to empty is