Download Forces in Fluids

Forces in Fluids
Chapter 11
Today we will…
Describe forces in fluids using Cornell
Notes
1. Pressure, floating, and sinking
2. Pressure – what is it?
3. Pressure = Force/area
3. The amount of pressure you exert depends
on the area over which you exert a force.
3. Measured in Pascals (Pa) = N/m2
3. Use a barometer to measure atmospheric
pressure
3. Discuss in your groups: Why do you sink in
snow with boots, but barely sink in the snow
with snowshoes?
2. Fluid Pressure
3. Remember – a fluid is a material that can easily flow
3. Particles move in all directions
3. All of the forces exerted by the individual particles
combine to make up the pressure exerted by the fluid.
3. Air fluid = atmospheric pressure
3. Balanced pressure – air pressure is
balanced on the Earth.
4. Discuss – what happens when it
becomes unbalanced?
4. Atmospheric pressure decreases as
your elevation increases
4. Atmospheric pressure increases as
depth increases
2. Floating or Sinking
3. Density – what is it?
4. Density = Mass/Volume
4. By comparing densities you can predict
whether an object will float or sink in a fluid.
4. Changes in density will cause an object to
sink – like the Titanic – or float like a beach
ball.
5. Density explains how a submarine
operates
2. Buoyancy
3. Buoyant force – what is it?
4. Water and other fluids exert an upward
force that acts on a submerged object
4. Acts in the direction opposite to the force
of gravity so it makes an object feel lighter.
4. The less dense the object, the greater the
buoyant force.
3. If the weight of an object is
a. greater than the buoyant force, it will sink
b. Less than the buoyant force, it will float
c. Equal to the buoyant force, it will not sink
3. Examples
a. Jellyfish – floats
b. Turtle – underwater but can float in place
c. lobster – more density than water and
unbalanced forces cause it to sink because they
are greater than the buoyant force
Warm- up
You have 10 Minutes to complete these…
Create a Vocab Map for the following terms:
Pressure
Density
Buoyant Force
Today we will…
Compare and contrast Archimedes’,
Pascal’s, and Bernoulli’s principles
using demonstrations and Cornell
Notes.
1. Principles of Forces in Fluids
2. Archimedes’ principle
3. Ancient Greek Mathematician
3. Principle states that the buoyant force acting
on a submerged object is equal to the weight of
the volume of fluid displaced by the object.
3. Examples:
4. Ship’s hull vs Piece of steel the same
weight
2. Pascal’s Principle
3. Blaise Pascal in 1600’s
3. Principle States that when force is applied
to a confined fluid, the change in pressure is
transmitted equally to all parts of the fluid.
3. Example – Squeezing a water bottle
2. Bernoulli’s Principle
3. Swiss Scientist in the 1700’s
3. Daniel Bernoulli
3. Principle states that as the speed of a
moving fluid increases, the pressure exerted
by the forces decreases.
3. Paper example
3. Applying Bernoulli’s principle
4. Explains how planes fly
4. Flying Frisbees
4. Smoke from a chimney
Homework
Concept Maps:
Bernoulli’s principle
2. Archimedes’ principle
3. Pascal’s principle
1.