Pressure in Liquids

• The amount of pressure inside a body of liquid increases with depth.
• At greater depths, the weight of the liquid above is greater.
• Therefore, the pressure is greater.

Pressure in Liquids Formula

• From the equation p= hpg, we can see that the pressure in a liquid increases with the depth and density of the liquid.
• It does not depend on the volume or cross-sectional area of the liquid.

Classic Pressure in Liquid Questions

1. Explain why the height of the mercury in a barometer remains unchanged when the diameter of the inverted tube is changed.

• Since Pressure = (height of liquid column) x (density of liquid) x (gravitational field strength)
• then the height = pressure / [(density of liquid) x (gravitational field strength)].
• It means that the height of the mercury in the barometer depends only on the pressure and gravitational field strength.