6. Fluids & Solids Flashcards
what are the 2 things that can be a fluid
gas or liquid
what is the molecular arrangement like in fluids and how do they move
not arranged in any order/structure and thus move in random directions relative to each other
what is density
amount of mass a fluid contains in a specific volume
what is the equation for density
p = m/V
what is the unit for density
g/cm^3
kg/m^3
put the following into order from greatest to least density
solid > liquid > gas
what does being least dense mean for gas
it can be compressed
are solids and liquids compressible in terms of the GAMSAT
no
what is specific gravity
ratio of density of substance to density of water
what is the equation for the specific gravity
SG = p(substance)/p(water)
p = density
if we want to calculate the specific gravity and the density is not known what do we do
use weight or mass of substance to find specific gravity
specific gravity will still be the same
what is the density of water
1g.ml = 1g/cm^3
same as 10^3kg/m^2
what does it mean relative to water if the specific gravity is less than one
substance is lighter than water
what does it mean relative to water if the specific gravity is less than one
substance is lighter than water
what does it mean relative to water if the specific gravity is more than one
substance is heavier than water
what does it mean relative to water if the specific gravity is equal to one
substance equally as heavy as water
what is the equation for pressure
P = F/A
F = perpendicular force to area in Newtons
P = pressure in pascal (1Pa = 1N/m^2)
what is pressure defined as
potential energy per unit volume
what is the equation for calculating pressure
P = pgh
p = density of gas or fluid (kg/m^3)
g = acceleration due to gravity (9.80m/s^2)
h = height of a column of gas or fluid (m)
at a certain depth what is known about the pressure of the fluid
it is the same in all directions
does the shape or surface area of the container affect fluid pressure
no
fluids exert forces that are always 90 degrees to what
to the surface of the container
the pressure of a fluid is directly proportional to what 2 characteristics of the fluid
its density and its depth
what is the buoyant force
when object is submerged in water the upward force that acts on submerged object is the buoyant force
what is achimedes principle
buoyant force is upward force that acts on submerged object and equal to weight of fluid that is displaced by the submerged object
what is the unit of pressure
Pascals (Pa)
what is the equation for buoyant force
Fb = p(fluid)Vg
the specific gravity of the fluid is equivalent to what characteristics of the object
the height of an object partially submerged in the fluid
what is laminar flow in terms of particle movement direction and rate
all particles in fluid are moving in straight line in the same direction
moving at the same rate
what is turbulent flow in terms of particle movement direction and rate
irregular flow of particles move in a state of chaos
some particles oppose the direction of others and cause collisions
what is the equation for calculating the rate of laminar flow through a pipe
Volume = cross sectional area x distance
Distance = velocity x time
so
Volume = cross sectional area x velocity x time
(V = Avt)
Rate = volume past a point/time
R = Avt/t
R = Av
what is the continuity equation
A1V1 = A2V2
A = cross sectional area
V = flow velocity
what is fluid velocity
resistance of fluid layers to flow past each other
what is the relatioship between velocity and speed
high velocity = slower
what is reynolds number used to determine
whether the flow of a fluid is laminar or turbulent
what is the equation for calculating reynolds number
R = vdp/n
d = diametre of tube
n = viscosity coefficient
what does it mean if reynolds number is <2000
flow in a pipe is generally laminar
what does it mean if reynolds number is >2000
flow is generally turbulent
what is surface tension
intensity of intermolecular forces per unit length
what does surface tension adirse from
an imbalance of the cohesive forces between molecules
which is the imbalance of the cohesive forces between molecules that surface tension arise from regarding molecules in bulk liquid
molecule in bulk liquid experiences cohesive forces with other molecules in all directions
which is the imbalance of the cohesive forces between molecules that surface tension arise from regarding molecules at the surface of liquid
molecule at surface of liquid experiences only net inward cohesive forces
what are the 2 components of elasticity in solids
stress
strain
what is stress in terms of elasticity for solids
ratio of force applied to object on area over which the force is applied
what is the unit for stress
N/m^2
what is strain defined as in terms of elasticity for solids
fractional change in dimension of object caused by stress
what is the unit of strain
it has no units
what is the relationship between stress and strain
proportional to each other
what is the modulus of elasticity
stress and strain are proportional and is given as a ratio
what is the equation for modulus of elasticity
ME = stress/strain
