Fluids and Solids Flashcards
density
how much mass it contains in a specific volume
= m/V
intensive property
kg/m^3
specific gravity
density of substance compared to density of water
denisty(s)/density(w)
lighter than water
>1 –> heavier than water
density of water
1000 kg/m^3
1 g/cm^3
fluid pressure results from…
impulse of molecular collisions
pressure =
Force/area = Pascal
gauge pressure
measure of the pressure compared to local atmospheric pressure, can be negative like when suck in air to lungs or drink through straw
for fluid at rest, P =
density of fluid x g x depth
atmospheric pressure =
101,000 Pa
absolute pressure
gauge pressure + atmospheric pressure
Pascal’s principle
pressure applied anywhere to an enclosed imcompressible fluid will be distributed undiminished throughout that fluid.
hydraulic lift equations
F1d1 = F2d2 F1/A1 = F2/A2
buoyant force / Archimedes’ principle
buoyant force is an upward force acting on a submerged object and is equal to the weight of the fluid displaced by the submerged object
F(b) = density(fluid)*V displaced fluid *g
uniform translational motion
motion of fluid as a whole, does not contribute to fluid pressure
ideal fluids…
no viscosity (tendency to resist flow)
incompressible; uniform density
lacks turbulence, has steady flow
experience irrotational flow
volume flow rate, Q
Q = Av
narrower pipe –> greater velocity –> decreased pressure
flow rate is constnat
Bernoulli’s equation
P + densitygh + 1/2densityv^2 = K
K = constant specific to a fluid in a given situation of flow
velocity of fluid coming from spigot =
v= sqrt(2gh)
in a horizontal pipe of constant cross-sectional area, fluid will flow from high pressure to low pressure according to the equation:
delta(P) = QR R = resistance to flow
stress
force applied to an object divided by the area over which the force is applied
use N/m^2
stress = F/A
strain
the fractional change in an object’s shape
ratio of change in dimension compared to original dimension, has no units
strain = change in dimension/original dimension
modulus of elasticity
proportionality between stress and strain
= stress/strain
constant for a specific substance
Young’s modulus
tensile stress, lengthening/shortening
shear modulus
shear stress, tilting..
bulk modulus
compression and expansion, from all sides
