Liquid pressure

• Calculating pressure in a liquid

  1. Place object in liquid

  2. Pressure due to surrounding water molecules colliding

  3. Pressure due to weight of water above object

  4. Pressure increases with depth as more water above object

  5. Pressure depends on density of liquid

  6. Pressure depends on gravitational field strength
• Pressure in a liquid

  Equals height of column of liquid above object x density of liquid x gravitational field strength
• Upthrust


  Upwards force on submerged object due to surrounding water molecules
• Upthrust on submerged object

  Depends on whether upthrust or object's weight is larger
• Floating vs sinking


  • If object is less dense than liquid, it floats
  • If object is more dense than liquid, it sinks
• Instead of calculating upthrust and weight, just need to know densities of object and liquid