Wk1 Flashcards
1
Q
what is shear stress?
A
parallel to surface
2
Q
what is normal stress?
A
perpendicular to surface
3
Q
define fluid
A
substance that deforms continuously under action of shearing forces however small
4
Q
what happens when a fluid is at rest?
A
no shearing force,
only enacts normal stresses on its bounding surface
5
Q
density equation
(unit?)
A
6
Q
density of water?
A
1000 kg / m3
7
Q
what is compressibility?
A
when put under pressure, the density increases
8
Q
what assumption do we use for fluids?
A
assume they are incompressible (constant density)
-fine for liquids
- for gases, only if the differences in pressure are relatively small
9
Q
define viscosity
A
The resistance of fluids to deformation is called viscosity
- fluid deforms continuously under a shearing force however small. Some fluids deform at a greater rate than others
10
Q
units for force
A
kgm/s^2
or
N
11
Q
units for stress
A
N/m^2
or
Pa
12
Q
A
13
Q
A
14
Q
A
15
Q
A
