GCSE Physics (AQA)

346 videos | 23 hours

Pressure of a Liquid Column

Please subscribe to watch this video.

This, and all other videos, are included in our premium subscriptions.

Premium accounts get access to all videos.

Forces Pressure and pressure differences in fluids

Pressure of a Liquid Column

4:34 Depth and Atmospheric Pressure
Spec 4.5.5.1.2
Previous Pressure & Depth Next Upthrust
  • Pressure due to a liquid column depends on the weight of the liquid.
  • Pressure is caused by the weight of the water above.
  • Pressure equation: Pressure = Height of column x Density of liquid x Gravitational field strength.
  • Density is mass per unit volume, indicating how heavy a substance is for a given quantity.
  • Gravitational field strength is the gravitational force acting on a mass of one kilogram.
  • The equation calculates pressure from the liquid above, not considering upthrust from below.
  • Symbol form of the equation: P = H x �� x G.
  • Pressure is force divided by area.
  • Pressure is measured in Pascals, height in meters, density in kg/m��, and gravitational field strength in N/kg.
  • Gravitational field strength changes with depth, but the equation is used for pressure depth problems in exams.
  • Example: A diver experiences 296 kPa pressure from water and air, with water density 1000 kg/m�� and air pressure 100 kPa.
  • Calculate water pressure: Total pressure - Atmospheric pressure = 196 kPa.
  • Convert units: 196 kPa = 196,000 Pascals.
  • Density = 1000 kg/m��, Gravitational field strength = 9.8 N/kg.
  • Height of the column is the same as depth.
  • Rearrange equation to find height: Pressure / (Density x Gravitational field strength) = Height.
  • Substitute values: Height = 196,000 / (1000 x 9.8) = 20 meters.

Please subscribe to access these revision notes.

This, and all other video notes, are included in our premium subscriptions.

Premium accounts get access to all videos and revision notes.