1. Forces in Fluids

2. What is pressure? The result of a force acting over a given area.
Pressure = Force/Area
Measured in N/m2
1 N/m2 is known as a pascal (Pa)

3. Blaise Pascal 1623-1662 French physicist and mathematician
Performed some of the first experiments dealing with pressure

4. Fluid pressure
Fluids: a substance that attains the shape of its container. Examples: both liquids and gases.
Fluid pressure changes with depth in a column of water and with altitude.
Fluid pressure in water does not depend on the volume or weight only the depth.

5. Pressure on a Diver

8. Air Pressure
The standard atmosphere (symbol: atm) is a unit of pressure equal to Pa It is equivalent to 760 mmHg or psi.
Air pressure will decrease with increases in altitude.
Examples: flying in a plane, driving in the mountains

9. Weather systems

10. Pascal’s Principle
A change in pressure at any point in a fluid is transmitted equally and unchanged in all directions throughout the fluid

13. Air Pressure
How it works
Handle
Handle
Vacuum
Air Tight Seal

14. hydraulics
Uses Pascal’s principle and moving pistons with an enclosed pressurized fluid:
Examples:
Car brakes, jacks, and loaders

15. Hydraulic Brakes

16. Problem:
If a force of 30 N is placed on a small piston of a hydraulic device with an area of 2 cm2, what size of a load can the larger piston lift if the area of the larger piston is 80 cm2?

17. Bernoulli’s principle
Swiss scientist
Explained the basis behind airplane flight.
As the speed of a fluid increase, the pressure decreases

18. Airplane forces:

19. Why is wing shaped the way it is?

20. Other applications of Bernoulli’s principle:

21. buoyancy
The ability of a fluid to exert an upward force on an object resulting in an APPARENT loss of weight of the object

22. Archimedes Greek mathematician 287-212 B.C.
Best known for his theory that the buoyant force on an object is equal to the weight of the fluid displaced

23. Archimedes
The Story

24. Application of buoyancy
Ballast tanks in submarines

25. “submarine” fish

26. Density Review D=M/V Density- the amount of matter in a space
Density of water is 1 g/ml or 1 g/cm3
What is the density of a piece of wood that has a mass of 25.0 grams and a volume of 29.4 cm3?