Fluids

• What is meant by the term ‘fluid’?


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

  At right angles (normal to) the surface.
• What is the equation used to calculate pressure?

  Pressure (Pa) = Force (N) / Area (m²)
• Why does atmospheric pressure vary with the height above the earth's surface?

  The number of air molecules decreases the higher you go, leading to decreased pressure.
• True or False: The pressure in a fluid is determined by the fluid and the atmospheric pressure.

  True
• In what direction does pressure act in a fluid?

  All directions.
• How does pressure in fluids increase with depth?

  As depth increases, the mass of the liquid above increases, leading to increased pressure.
• Why does pressure in fluids increase with density?

  As density increases, there are more particles in a given volume, increasing the weight and pressure.
• What equation shows the magnitude of pressure in liquids at different depths?

  Pressure (Pa) = Column height (m) x density (kg/m³) x gravitational field strength (N/kg)
• Why are objects in a fluid subject to an upthrust?

  Objects submerged in fluid experience higher pressure below than above, leading to an upwards force called upthrust.
• What is the magnitude of the upthrust felt by an object?

  Upthrust is equal to the weight of fluid displaced by the object.
• How can you determine if an object will sink or float?

  If the upthrust is greater than the weight of the object, it will float; if the weight is greater, it will sink.
• Explain why an object with a density more than that of water would never float.

  Upthrust equals the weight of the displaced fluid; if the object's density is high, it won't displace enough fluid to produce sufficient upthrust to float.