Fluid Dynamics
Factors Affecting Fluids
SCI 8: Fluids Unit
Curriculum Outcomes Addressed:
- Explain quantitatively the relationship between force, area, and pressure
- Explain qualitatively the relationship among pressure, volume, and temperature when liquid and gaseous fluids are
compressed or heated (309-4)
Key Terms
• Compress: To decrease the amount of space or
volume available for a fluid
• Expand: To increase the amount of space or
volume available to a fluid
• We have studied the following properties of fluids:
1. Density (amount of matter per unit volume)
2. Volume (amount of space occupied by a fluid)
3. Pressure (amount of force per unit volume)
4. Viscosity (flow rate)
• Now we will look at how these properties are related
and how they influence each other and work together
to determine fluid dynamics. We will also look at how
temperature plays a role in determining changes in
these properties.
Factors Affecting Fluids:
TEMPERATURE and Particle Bond Strength
• There is a direct relationship between temperature
and the strength of bonds between particles in
fluids.
• As the temperature of a fluid increases, its particle
bond strength decreases.
• Can you think of an example of this relationship in
everyday life?
Factors Affecting Fluids:
TEMPERATURE and Particle Bond Strength
• As the temperature of a fluid increases, its particle
bond strength decreases.
• Can you think of an example of this relationship in
everyday life?
• Using warm water works better when you try to
remove a stain or dirt from an object because the
warmth loosens the bonds between the particles,
allowing them to separate better.
Factors Affecting Fluids:
TEMPERATURE and DENSITY
• As we have seen, there is a direct relationship
between temperature and the density of fluids.
• As the temperature of a fluid increases, its density
decreases.
• Can you think of an example of this relationship in
everyday life?
Factors Affecting Fluids:
TEMPERATURE and DENSITY
• As the temperature of a fluid increases, its density
decreases.
• How can you explain this relationship using the
Particle Theory of Matter?
• Density columns: Cold water at the bottom, room
temperature water in the middle, and hot water at the top.
Factors Affecting Fluids:
TEMPERATURE AND VOLUME
• There is a direct relationship between temperature
and the amount of volume taken up by a fluid.
• As the temperature of a fluid increases, the
amount of volume it takes up increases. This is
particularly true for gases.
• Can you think of an example of this relationship in
everyday life?
Factors Affecting Fluids:
TEMPERATURE AND VOLUME
• As the temperature of a fluid increases, the amount of
volume it takes up increases. This is particularly true
for gases.
• Can you think of an example of this relationship in
everyday life?
• A basketball that is left outside the sun will be more
pumped up than a basketball that is left outside in
the cold. This is because the sun warms up the
particles inside the ball, weakening the bonds
between them, and allowing them to move faster,
and spread farther apart, taking up more volume.
Factors Affecting Fluids:
TEMPERATURE AND VOLUME
• As the temperature of a fluid increases, the
amount of volume it takes up increases.
Factors Affecting Fluids:
TEMPERATURE AND PRESSURE
• There is a direct relationship between temperature
and the pressure inside a fluid.
• As the temperature of a fluid increases, the
pressure of a fluid in a closed space increases.
• Can you think of an example of this relationship in
everyday life?
Factors Affecting Fluids:
TEMPERATURE AND PRESSURE
• As the temperature of a fluid increases, the pressure
of a fluid in a closed space increases.
• Can you think of an example of this relationship in
everyday life?
• When you try to fit a gas into a smaller space
(volume), the pressure inside increases. For example,
when you squeeze a balloon that is filled with air, the
pressure builds up inside to the point that it might
burst if you decrease the volume inside too much.
Factors Affecting Fluids:
TEMPERATURE AND VISCOSITY
• As we have seen, there is a direct relationship
between temperature and the viscosity of fluids.
• As the temperature of a fluid increases, its
viscosity decreases.
• Can you think of an example of this relationship in
everyday life?
Factors Affecting Fluids:
TEMPERATURE AND VISCOSITY
• As the temperature of a fluid increases, its viscosity
decreases.
• How can you explain this relationship using the
Particle Theory of Matter?
• A liquid at a warmer temperature flows more
easily/quickly than a liquid at a colder temperature.
For example, if you can’t get honey to flow out of its
container, you can warm it up in the microwave for a
few seconds until it flows out.
How Temperature Affects Fluids
• Fill out the table below to show the relationship between
BONDcompression, and fluid properties.
temperature,
STRENGTH
As
Temperature
INCREASES…
As
Temperature
DECREASES..
VOLUME
DENSITY
VISCOSITY
PRESSURE
Factors Affecting Fluids
• PHET SIMULATION of how temperature and
compression affect the density, volume, and
pressure of fluids.
http://phet.colorado.edu/en/simulations/categor
y/physics/work-energy-and-power
WATER: An Exception
• Water is an exception to many fluid dynamic relationships.
• Water has a greater volume at a high temperature (it goes
from liquid to gas form), but when water freezes at low
temperatures, its volume ALSO increases (like when you
freeze a plastic bottle of water and the plastic breaks).
• The density of water also doesn’t follow the typical fluids
rule. Frozen water (ice) is less dense than liquid water, so
ice floats in water. Could you imagine what the world would
be like if water did follow the typical fluids rule that frozen
fluids are more dense than liquid fluids of the same kind?
What would the world look like?