1. Forces In Fluids

2. Fluids include: Liquids and Gases
Fluid – any material that can flow and takes the shape of its container
Fluids include: Liquids and Gases

3. Flow happens when particles move easily past each other

4. Air pressure and water pressure?
All fluids exert pressure

5. Pressure – amount of force exerted on a given area

6. Force Pressure = Area Pressure is measured in: pascals (Pa) Equation:
1 Pa is the force of 1 N exerted over an area of 1 square meter

7. Force
Area
Pressure =
What is the pressure exerted by a book that has an area of 0.2 m² and a weight of 10 N?

8. Find the pressure exerted by a 3000 N crate that has an area of 2 m².
Force
Area
Pressure =
Find the pressure exerted by a 3000 N crate that has an area of 2 m².

9. Force
Area
Pressure =
Find the weight of a rock that has an area of 10 m² and that exerts a pressure of 250 Pa.

10. Fluids exert pressure evenly in all directions
When you blow a bubble, you blow in only one direction. So why does the bubble get rounder instead of longer as you blow?
Fluids exert pressure evenly in all directions
Bubbles: expand in all directions to make a sphere

11. layer of nitrogen, oxygen, and other gases surrounding the earth
Atmosphere
layer of nitrogen, oxygen, and other gases surrounding the earth
What keeps those gases from floating away?

12. Atmospheric pressure
pressure caused by the weight of the atmosphere

13. Atmospheric pressure is exerted on everything on Earth
At sea level, you have a weight of about 10 N (2lbs) pushing on every cm2 of your body
Why don’t you feel it?
Fluids inside us push back

14. Pressure inside = Pressure outside

15. Atmosphere stretches about 150 km above the Earth’s surface
Atmosphere stretches about 150 km above the Earth’s surface. However, 80% of the atmospheric gases are found in the 10 km

16. Differences in Atmospheric Pressure
At sea level – full weight of atmosphere (101 kPa) is exerted on you

17. Differences in Atmospheric Pressure
La Paz, Bolivia (world’s highest capital city at 4000 m) has atmospheric pressure of 51 kPa

18. Differences in Atmospheric Pressure
Mt. Everest is the highest point in the world and has an atmospheric pressure of 33 kPa

19. Differences in Atmospheric Pressure
Atmospheric pressure at m is about 20 kPa. Airplane cabins must be pressurized for passenger safety

20. Differences in Atmospheric Pressure
At 150,000 m above sea level, atmospheric pressure is almost 0 Pa. Major protection is needed

21. As you increase in altitude, what happens to the atmospheric pressure?
DECREASES

22. Altitude Sickness?
Exposure to low oxygen levels from 2,400 m above sea level

23. Water Pressure

24. Water pressure increases as depth increases

25. Water is about 1,000 times more dense than air
Water exerts more pressure than air

26. If you climb a 10 m tree, the decrease in pressure is too low to notice. If you dive 10 m below water, pressure almost doubles

27. Differences in Water Pressure
At 10 meters below the surface, pressure is about 100 kPa

28. Differences in Water Pressure
At 500 m below the surface, pressure is about 5,000 kPa. Divers have to wear special suits to survive the pressure.

29. Differences in Water Pressure
The wreck of the Titanic is 3,660 m below. Water pressure is 36,600 kPa

30. Differences in Water Pressure
Viperfish live 8,000 m below and no fish are found lower. Pressure is 80,000 kPa

31. Differences in Water Pressure
In 1960, the Trieste descended to the deepest part of the ocean (11,000 meters) where water pressure is 110,000 kPa

32. As you move deeper, the pressure increases

33. Diving sickness Increasing pressure to the body too quickly
nitrogen gas bubbles are released into the bloodstream and tissues, which can cause numbness, dizziness, weakness, nausea, pain, headaches, itching, and visual disturbances.

34. Fluids flow from areas of high pressure to low pressure

35. You can see this in…
Soda Can
Breathing
Tornadoes

36.  gas inside the can is more pressurized than gas outside so when opened, gases will escape

37. Inhale
diaphragm contracts making lung space increase.

38. Inhale
Air pressure outside is higher so it flows into lungs

39. Exhale
diaphragm relaxes making lung space decrease

40. Exhale
Air pressure inside lungs is greater so it flows outside body

41. Tornadoes
Air pressure inside tornado is low while air pressure outside is high. This causes air and other objects in its path to be sucked into the tornado

42. Mythbusters Pressure Differential