Floating or sinking

• what equation shows the magnitude of pressure in liquids at different depths?

  pressure due to a column of liquid (Pa) = column height (m) x density (kg/m cubed) x gravitational field strength (N/kg)
• why are objects in a fluid subject to an upthrust?

  when an object is submerged in a fluid, it has a higher pressure below it than it does above, as there is more weight above it at the bottom than there is at the top. this leads to an upwards force called upthrust. you float or sink depending on whether the upthrust is more or less than your weight.
• what is upthrust always equal to?

  the weight of the fluid that the object displaces
• what factors influence whether an object will sink or float?

  • upthrust
  • weight
  • density of fluid
• explain why an object with a density greater than that of water can never float.

  upthrust is equal to the weight of the displaced fluid. if the density of the object is high, there would not be enough volume displaced to produce an upthrust larger than the object’s weight. this means that it will sink.