Ontario Operator-in-Training (OIT) Practice Exam

What determines the pressure head at the bottom of a water column?

1. The volume of water in the tank

2. The height of the water column

3. The temperature of the water

4. The speed of the water flow

The correct answer is: The height of the water column

The pressure head at the bottom of a water column is primarily determined by the height of the water column. This concept is rooted in the principles of hydrostatics, which state that the pressure exerted by a fluid in a column is directly proportional to the height of that fluid and the density of the fluid, along with gravitational acceleration. As the height of the water column increases, the weight of the water above it generates more pressure at the base of the column. In practical terms, for each unit of height (often measured in meters), there is a corresponding increase in pressure, typically calculated using the formula P = ρgh, where P is pressure, ρ is the fluid density, g is the acceleration due to gravity, and h is the height of the water column. Therefore, the taller the column of water, the greater the pressure experienced at the bottom. The other factors mentioned, such as the volume of water in the tank, the temperature of the water, and the speed of water flow, do not directly determine the pressure head. While the volume can affect the height of the water column indirectly, it’s the height itself that ultimately drives the pressure. Temperature can influence fluid density but does not impact the pressure head directly