BRAINCAKEPressure in Fluids and Archimedes Principle
Gases and Liquids (fluids) exert pressure on surfaces because of the constant collisions of their molecules with the surfaces. The force exerted by a column of liquid on a surface is its weight.
Since density ρ = mass per unit volume the weight of the column is given by mass × g which equals (ρV) × g.
The volume V of the column is A×h where A is the cross-sectional area and h is the height of the column.
Therefore the pressure is given by force / Area
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Key terms in this lesson
- resultant
- The single force or vector that has the same effect as two or more forces or vectors acting together.
- weight
- The gravitational force acting on an object's mass.
- density
- The mass per unit volume of a substance.
- pressure
- The force acting per unit area, at right angles to a surface.
More in Forces and Motion
- Weight, Mass, Accleration
- Centre of Mass
- Free-Body Force Diagrams
- Drag and Terminal Velocity
- Moments and Equilibrium
- Couples and Torques
- Forces in Equilibrium
- Density and Pressure
All 17 lessons in Forces and Motion · All OCR AS-level Physics topics