Two tanks have different shapes but the same water height, with pressure gauges at their bottoms. Which statement is true?

• A. Tank B gauge is dependent on the shape
• B. Tank A gauge will read the same as the Tank B gauge
• C. A is 10x higher
• D. 10x higher

Answer: (B)

The pressure at the bottom of a static water column depends on the height of the water above, the water’s density, and gravity, not on the tank’s shape or volume. This hydrostatic principle means P = ρgh, so if both tanks have the same water height, the bottom pressures are the same. The gauges read the same because they are measuring this bottom hydrostatic pressure, assuming both are open to the atmosphere and measuring gauge pressure. Different shapes or amounts of water don’t change the pressure at the bottom when the vertical height is equal.