8. Hydrostatics
8.1 Hydrostatics as a part of mechanics
 | Hydrostatics is the study of incompressible fluids that are
at rest and in equilibrium.
|
| Mechanics also includes the study of fluids in motion, fluid
dynamics, but this is one of the most complex branches of
mechanics and will not be studied on this course. |
8.2 Density
| Density = mass / volume ρ
= m/V
|
| In the SI system, density is measured in units of kilograms per cubic
meter (kg/m3).
|
| The density of water = 1000 kg/m3 and the density of air = 1.2 kg/m3
(atmospheric pressure, 20°C). |
8.3 Pressure
| The application of a force over an area produces pressure.
|
| When the force is perpendicular to the surface area, the pressure equals
the force divided by the area over which it acts.
Pressure = Force /
Area
P = F/A
|
| Pressure is a scalar quantity measured in N/m2 or pascals (Pa)
in the SI system
|
| A pressure of 1 pascal (Pa) is equivalent to a force of 1 newton acting on
each square meter.
|
| Pressure can also be measured in atm, bars, millibars, mm Hg, psi ...
|
| Atmospheric pressure is surprisingly high: just over 100 kPa |
8.4 Archimedes' and Pascal's Principles
| Archimedes' principle: any completely or partially submerged object
experiences an upthrust or buoyant force equal to the weight of the fluid
displaced by the object.
|
| Pascal's principle: The pressure applied at one point in an
enclosed fluid under equilibrium conditions is transmitted equally to all
parts of the fluid. |
|
|
