🔍 Key Concepts

• hydrostatic (head) pressure in a liquid and how it varies with depth • the role of liquid density in calculating pressure at a given depth • how a pneumercator (bubble-type level gauge) actually operates in a tank

💭 Think About

• If the device uses bubbles/air pressure to determine level, what physical quantity is it actually measuring? • Does the instrument have any sensor that detects changes in density directly, or does it assume density is known/constant? • If the same instrument were used on two different liquids at the same depth, what would change and what would stay the same in its measurement?

✅ Before You Answer

• Be clear on the difference between what is sensed (measured by the instrument) vs. what must be known or assumed (entered or calibrated by the operator). • Consider whether the gauge would react to a change in liquid density if the level stayed the same. • Verify how hydrostatic pressure = depth × density × gravity relates level, pressure, and density.