Pressure and Pressure difference in Fluids

• What is meant by the term ‘fluid’?

  A liquid or a gas
• At what angle do forces due to pressure act on a surface in a fluid?

  At right angles to the surface
• What is the equation used to calculate pressure?

  Pressure = Force/Area
• What are the units for pressure, force, and area?

  Pressure (Pascals), Force (Newtons), Area (metre²)
• What happens to the density of the atmosphere with increasing altitude?

  The atmosphere becomes less dense
• Why does atmospheric pressure decrease with an increase in height?

  Fewer air molecules lead to lower pressure
• What is the Earth's atmosphere?

  A thin layer of gas surrounding Earth
• How does pressure in fluids increase with depth?

  Mass of liquid above increases with depth
• Why does pressure in fluids increase with density?

  More particles lead to greater weight
• What equation shows the magnitude of pressure in liquids at different depths?

  Pressure = height x density x gravitational strength
• What is the formula for pressure due to a column of liquid?

  P = hρg
• Why are objects in a fluid subject to an upthrust?

  Higher pressure below than above the object
• What is upthrust always equal to?

  The weight of the displaced fluid
• What factors influence whether an object will sink or float?

  • Upthrust
  • Weight
  • Density of fluid
• Why can an object with a density greater than water never float?

  Not enough volume to displace sufficient fluid