Pressure in a Fluid

• When does an object float?

  An object floats if its weight is less than the weight of the water it displaces.

  So a 1000kg boat will sink into the water until it has displaced 1000kg of water, then it will float
• What does pressure in a liquid vary with?

  Depth and density, and this leads to an upwards force on a partially submerged object
• What is the upwards force?

  A buoyancy force that counteracts the weight of the floating object

  This is equal to the weight of the fluid displaced by the object
• What is the equation of pressure due to a column of liquid?

  Pressure = height of column x density of liquid x gravitational field strength

  $p=$$h\rho g$
• What happens to pressure on a large surface area?

  Pressure is reduced
• What happens to pressure on a small surface area?

  Pressure is increased
• a.) Pressure increases with depth

  b.) Pressure is the same at the same depth