1. Characteristics of Fluids
Archimedes’ Principle
Pascal’s Principle
Bernoulli’s Principle

2. How do fluids respond to weight and/or pressure?
Essential Question
How do fluids respond to weight and/or pressure?

3. Buoyant Force
Buoyant Force: The upward force or push a fluid exerts on an object in that fluid.
Caused by a difference in pressure. The deeper you go in a fluid the higher the pressure. (remember the tennis ball container)
If the buoyant force ↑ is less than the objects weight ↓ it will sink.
If the buoyant force ↑ is equal to the objects weight ↓ it will float.
If the buoyant force ↑ is greater than the objects weight ↓ it will rise up.
show pHet Sim: Ballons and Buoyancy

4. Archimedes' Principle
Archimedes Principle: The buoyant force on an object is equal to the weight of the fluid displaced by the object.
Weight of object = Weight of fluid displaced
Object floats
Weight of object > Weight of fluid displaced
Object sinks
Weight of object ‹ Weight of fluid displaced
Object rises up
What is the fluid being displaced in this picture?
What is the weight of this fluid?

5. Archimedes Principle

6. Demo of Arch. Principle Object Mass Weight of Object (m x .00982)
Weight of object = Weight of fluid displaced
Object floats
Weight of object > Weight of fluid displaced
Object sinks
Weight of object ‹ Weight of fluid displaced
Object rises up
Demo of Arch. Principle
Object
Mass
Weight of Object
(m x )
Mass of Displaced Water
Weight of Water
Candle
Plastic Cube
Metal Cylinder
Gas Spigot

7. Pascal’s Principle
Pascal’s Principle: Pressure applied to a fluid is spread evenly and unchanged throughout the fluid.
Example:
When you squeeze one end of a balloon the other end pops out.
Wherever you squeeze a tube of toothpaste the paste comes out.

8. Hydraulic Lift

9. Hydraulic Lift Drawing

10. Bernoulli’s Principle
Bernoulli’s Principle: As the speed of a fluid increases the pressure exerted by the fluid sideways decreases.
Example:
blow over the top of a piece of paper
Airplane Wing
Blowing Between 2 pop cans

11. Airplane Wing

12. Airplane Wing

13. Pop Can Drawing