9.11 - Liquid Pressure & Upthrust

Pressure in a liquid increases with depth and density

• At a point inside a liquid, the pressure comes from the weight of the column of liquid directly above that point.
• In a fluid at rest, the pressure at any point acts equally in all directions.

Pressure increases with depth

• Going deeper means a taller column of liquid sits above the point.
• The extra weight adds to the pressure, so the deeper you go, the higher the pressure.

Pressure increases with density

• A denser liquid has more mass in a given volume, so the column above a point weighs more - creating a higher pressure at the same depth.
• Liquids can be squashed only slightly, so their density is treated as constant throughout.