FLUIDS Flashcards
The density of a substance of uniform
composition is defined as its____
mass per unit volume
The densities of most liquids and solids vary
slightly with changes in ____ and
____
temperature and pressure
The ____ of a substance is the ratio of
its density to the density of water at 4° C
specific gravity
Specific gravity is a ____ quantity
dimensionless
The force exerted by a
fluid on a submerged
object at any point is
perpendicular to the
surface of the object
Pressure
A change in pressure
applied to an enclosed
fluid is transmitted undiminished to every point
of the fluid and to the walls of the container.
Pascal’s Principle
Pressure Measurements: ____
o One end of the U- shaped tube is open to
the atmosphere
o The other end is connected to the
pressure to be measured
o If P in the system is greater than
atmospheric pressure, h is positive
* If less, then h is negative
Manometer
Pressure Measurements: ____
o Invented by Torricelli (1608 – 1647)
o A long closed tube is filled with mercury and
inverted in a dish of mercury
o Measures atmospheric pressure as ρgh
Barometer
Blood pressure is measured with a special
type of manometer called a ____
Sphygmomanometer
Any object completely or partially submerged in
a fluid is buoyed up by a force whose magnitude
is equal to the weight of the fluid displaced by the
object
Archimedes Principle
The physical cause of the ____ is the
pressure difference between the top and the
bottom of the object
buoyant force
Whether an object sinks or floats depends on the
relationship between the ____ and the
____
bouyant force and the weight
o The object is less dense than the fluid
o The object experiences a net____force
o The object is more dense than the fluid
o The net force is ____
o The object accelerates ____
- Less dense
- upward
- more dense
- downward
- downward
Every particle that passes a particular point moves exactly along the smooth path followed by particles that passed the point earlier
* Also called laminar flow
Streamline Flow`
o The flow becomes irregular
* Exceeds a certain velocity
* Any condition that causes abrupt
changes in velocity
Turbulent Flow
the degree of internal friction in
the fluid
o The internal friction is associated with the
resistance between two adjacent layers of
the fluid moving relative to each other
Viscosity
Characteristics of an Ideal Fluid
- the fluid is (1___)
* There is no internal friction
between adjacent layers - the fluid is (2___)
* Its density is constant - the fluid motion is (3. ___)
* The velocity, density, and pressure
at each point in the fluid do not
change with time - o The fluid moves without ____
* No eddy currents are present
* The elements have zero angular
velocity about its center
- Nonviscous
- incompressible
- steady
- turbulence
The product Av is called the ____
o The equation is a consequence of
conservation of mass and a steady flow
Flow rate
o 1700 – 1782
o Swiss physicist and
mathematician
o Wrote
Hydrodynamica
o Also did work that
was the beginning
of the kinetic
theory of gases
Daniel Bernoulli
o Relates pressure to fluid speed and elevation
o ____ is a consequence of
Conservation of Energy applied to an ideal
fluid
o Assumes the fluid is incompressible and
nonviscous, and flows in a nonturbulent,
steady-state manner
o States that the sum of the pressure, kinetic
energy per unit volume, and the potential
energy per unit volume has the same value
at all points along a streamline
Bernoulli’s Equation
Applications of Bernoulli’s Principle: ____
o Shows fluid flowing through a horizontal
constricted pipe
o Speed changes as diameter changes
o Can be used to measure the speed of the
fluid flow
o Swiftly moving fluids exert less pressure
than do slowly moving fluids
Measuring Speed
Applications of Bernoulli’s
Principle: ____
o The height is higher in the
constricted area of the
tube
o This indicates that the
pressure is lower
o If objects A and B are separately in thermal
equilibrium with a third object, C, then A and B
are in thermal equilibrium with each other
– Object C could be the thermometer
o Allows a definition of temperature
Venturi Tube
