The Irish scientist Robert Boyle investigated the relationship between pressure and volume in the 17th century. He trapped a bubble of air at the sealed end of a J-shaped tube using liquid mercury.

Figure 14. One-dimensional duct showing control volume. When streamlines are parallel the pressure is constant across them, except for hydrostatic head differences (if the pressure was higher in the ...

The pressure exerted by a solid object which is resting on top of another solid surface is the weight of the object divided by the area of the object's surface. The formula for pressure is ...