Hydrostatics and Hydrodynamics Flashcards
Fluid Mechanics
The study of the physics of the continuous materials which take the shape of their container
density
p = m/v
archimedes principle
when a body is partially or completely immersed in a fluid, the fluid exerts an upward force on the body equal to the weight of the fluid displaced by the body
pressure in fluid
p = force/unit area
pressure and depth
weight of fluid not negligible, consider element of area, A, thickness, dy. At rest the forces are blanked
dp/dy = -pg
pressures at 2 vertical locations
p = po + pgh
pascal’s law
pressure applied to an enclosed fluid is transmitted undiminished to every portion of the fluid and to walls of the containing vessel
hydraulic lift
F2 = F1 (A2/A1)
and work done
F2h2 = F1h1
Oil and water
p = po + pwater ghwater
p = po + poil*hoil
hoil = pwater/poil hwater
viscosity
a measure of the internal friction of a fluid. Has important consequences for flow of the fluid and things like lubrication
viscosity is strongly dependant on
temperature
Δp ∝
L/R^4
buoyancy
an object partially or wholly immersed in a liquid seems to weigh less than it does in air
sink
if m object > m fluid
then p object > p fluid
float
if m object < m fluid
then p object < p fluid
at equilibrium
total weight of object equal to weight of displaced fluid
surface tension
due to attractive forces between molecules.
molecules at the surface are drawn towards the centre.
droplets tend to minimise surface areas and free falling droplets are spheres.
fluid flow
incompressible and internal friction free motion of fluid traced out by small particles
streamlines
v points in the same direction
parallel to each other
