Depending on where the inlet holes are located on the probe, it can measure static pressures or stagnation pressures. Surface pressure and surface tension
There is a two-dimensional analog of pressure – the lateral force per unit length applied on a line perpendicular to the force. Surface pressure is denoted by π:

  
    
      
        π
        =
        
          
            F
            l
          
        
      
    
    {\displaystyle \pi ={\frac {F}{l}}}
  and shares many similar properties with three-dimensional pressure. Properties of surface chemicals can be investigated by measuring pressure/area isotherms, as the two-dimensional analog of Boyles law, πA = k, at constant temperature. Surface tension is another example of surface pressure, but with a reversed sign, because "tension" is the opposite to "pressure". Pressure of an ideal gas
In an ideal gas, molecules have no volume and do not interact.
Mathematically, it is described by Bernoullis equation, where velocity head is zero and comparisons per unit volume in the vessel are

  
    
      
        
          
            p
            γ
          
        
        +
        z
        =
        
          c
          o
          n
          s
          t
        
        . {\displaystyle {\frac {p}{\gamma }}+z=\mathrm {const} .} Terms have the same meaning as in section Fluid pressure. Direction of liquid pressure
An experimentally determined fact about liquid pressure is that it is exerted equally in all directions. If someone is submerged in water, no matter which way that person tilts their head, the person will feel the same amount of water pressure on their ears.