Download States of Matter Part 3

F. Properties of Fluids
1. Archimedes’ Principle
a. Fluids exert an upward force on
objects. It is called the buoyant force.
b. The buoyant force is equal to the
weight of the fluid displaced.
If the weight of the displaced fluid
equals the weight of the object, the
object floats.
Fbuoy
Fw = Fbuoy
Fw
Object floats
If the weight of the displaced water is
less than the weight of the object, the
object sinks.
Fbuoy
Fw > Fbuoy
Object sinks
Fw
How can a steel ship float?
The hull contains mostly air and
displaces a lot of water...enough so
that Fbuoy = Fw and it floats.
2. Pascal’s Principle
a. Pressure is force per unit area.
P=F/A
b. Pressure applied
to a fluid is
transmitted
throughout the fluid.
F1
A1
The Pascal (Pa)
is the SI unit for
pressure
A2
F2
3. Bernoulli’s Principle
a. As the velocity of a fluid
increases, the pressure exerted by the
fluid decreases.
lower pressure
oncoming air
lift
b. The curved upper surface of a
wing causes the air to flow over it
faster and creates lower pressure
above the wing. This makes lift.
4. The Venturi Effect
a. Fluids flow faster in narrower
spaces and create lower air pressure
inbetween them.
b. Strong wind
between buildings.
c. Big trucks
passing small cars.
d. Landscapers use trees to
channel and create wind.
5. Viscosity
a. The resistance
of a fluid to flow.
b. Higher
temperatures increase
the movement of fluid
particles and make
them flow easier
(lowers their
viscosity).
An experiment to
measure the
viscosity of tar