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Pascal & Bernoulli
Page 90
Pascal
Movement of sea star is caused by pressure changes in fluid tubes within its body
90
Transmitting Pressure
1600’s French Scientist Blaise Pascal studied fluid pressure
What happens when you press on a closed bottle?
91
Pascal’s Principle
When a force is applied to a confined liquid, the change in pressure transmitted equally to all parts of the fluid
91
Hydraulic Systems
Closed fluid system to take advantage of Pascal’s principle
92
Hydraulic Systems
How does the force applied match the force transmitted?
Same
92
Hydraulic Systems
System B (larger side in 20 X)
20 X more force
92
Hydraulic Systems
How?
Uses fluid to transmit pressure equally
92
Hydraulic Systems
Car Breaks
94
Review
What is Pascal’s principle?
What is the device that uses this system?
Hydraulic System
What is the force? F = Pressure x Area
If pressure is 2 Pa and area is 10 m2
F = 2 Pa x 10 m2
F = 20 N
Bernoulli’s Principle
1700’s Swiss Scientist Daniel Bernoulli
Principle = As the speed of a moving fluid increases, the pressure within the fluid decreases
96
Paper
Take a sheet of paper and hold the corners.
Blow across the top of the paper
What happens?
Why?
Air pressure below is
higher so it pushes the
paper up
95
Ca ns
96
Applying Bernoulli
Objects are designed so that the change shape causes a change speed of air
97
Applying Bernoulli
If air moves faster above, how does the object move?
97
Applying Bernoulli
If air moves faster below, how does the object move?
97
Applying Bernoulli
Draw the air flow of a wing.
Air moving over the top exerts less …
97
Applying Bernoulli
Lift is another term for upward force
97
Chimneys
98
Atomizers
98
Flying Discs
99
Bat Wings
Read story
1. What would a bat use to land? Why?
2. Which would the bat use to catch bugs? Why?
3. Average flying? Why?
4. What would happen if one wing a and the other c? Why?
5. Why never use d?