Pressure in liquid

• Pressure unit

  Pascal (Pa)
• factors which determine the pressure exerted by liquid are:

  -The depth. At a greater depth, more pressure is exerted.

  -The density of the liquid. More dense liquids exert greater pressure

  -The gravitational field strength, which is 9.8 N/m on earth. 
• salt water is denser than fresh water so applies greater pressure
• The denser the liquid, the greater the upthrust it will exert on an object
• Upthrust is in the opposite direction to the weight
• If the upthrust on an object is equal to (or greater than) the object’s weight, then the object will float
• If the upthrust is smaller than the weight then the object will sink
• if a object has a density less than the density of the fluid it is immersed in, the object will float
• if a object  has a density more than the density of the fluid it is immersed in, the object will sink
• Objects which are less dense than water will float and which are more dense will sink
• upthrust


  the force caused by the difference in pressure on the top and bottom surfaces of a submerged object.
• Why are liquids used in hydraulics?

  incompressible
• Pressure formula 


  height x density x field strength
• density unit


  kg/m^3
• field strength unit 


  N/kg
• height unit


  meter