1. Water properties Water Quality/chemistry Water-the universal solvent
Dissolved Oxygen
Turbidity
Acid/base
Nitrogen cycle (ammonia, nitrite, nitrate)
Phosphates & Eutrophication
Hard and Soft water
Conductivity of water
Alkalinity
Water Physical properties
Water pressure & Pascal's principle
Scuba diving & dissolved gasses at pressure
Surface Tension
Heat capacity
Buoyancy & Archimedes principle
Density & the water density anomaly
Bernoulli’s principle

2. Fluid = gases & liquids
Fluid = A fluid is a substance that easily and continually deforms (flows) under an applied force
Pressure of a fluid (gas and liquid) is the sum of all collisions of the particles on the substance

3. 1) Pascal’s Principle
Pressure applied to fluid in a closed container is equally transmitted to all parts of the fluid and the container.
Think toothpaste…

4. 1) Applications of Pascal’s Principle…
We use pascal’s principle a lot in things that need power… car jacks, car brakes, tractors & construction machines
Under water, the weight/pressure of the water is a “squeeze” not a downward weight

5. 2) Effect of pressure on dissolved gas

6. Summary: There are several problems associated with scuba
1) Pressure is crushing even a small distance under the water (pascal’s principle)
2) Breathing air that is under pressure makes you a soda can!
a) blood dissolves more air with pressure
b) coming up fast can cause bubbles in your veins = painful… and deadly

7. 4) Remember “convection”
Heat makes things expand and rise
Cold makes things contract and sink
If one place is hotter,… what will happen to the air above it and thus the wind?

8. 4) The “Sea breeze”… that all coastal people know about.

9. 5) Buoyancy
Tankers are made of steel and weigh as much as 585,000 tons!!!
They are 1500 ft long, 225 ft wide… and extend >50 ft into the water!
How do they float?

10. 5) The Buoyant Force is why…
--- some things float and sink & why even things that sink feel lighter in water

11. 5) Archimedes principle

12. 5)Archimedes’ Principle
Buoyant force = weight of fluid displaced

13. 5) Archimedes Example

14. 5) Archimedes principle: example

15. 5) Archimedes Example 2 lb fish, displacing 2.5lbs of water 2 lb fish,

16. 6) Water’s density anomaly

17. 6) MOST things are denser as solids – lamp oil “ice” vs water “ice”
Most things continue to shrink as they “freeze” so the solid form is denser than the liquid form
H2O is the only compound we know of that expands when it freezes.
Solid water takes up more space than the same mass of liquid water… so due to Archimedes principle… it floats.
CAREFUL!!! – some of you have heard something I didn’t say! Liquid water still, in general, shrinks as it gets colder!!!!!!!!!!!!!!!!!!!

18. Water is unique!!!!!
Ice has a density
of 920 kg/m3

19. 6) Ever heard of a lake “turning over?”8 8 8 8

20. 7) Bernoulli’s Principle
The pressure of a fluid (gas or liquid) decreases as the fluid’s velocity increases.

21. 7) Bernoulli’s Principle
The pressure of a fluid (gas or liquid) decreases as the fluid’s velocity increases.

22. 7) Does Bernoulli's principle apply to water too?
Of course, it applies to all fluids (gas & liquids)
Sharks especially use it to stay up… they normally sink if they stop moving.

23. Reminder: know them by name
We have talked about three principles that describe some physical properties of water
Can you match them with their correct property:
Bernoulli Archimedes Pascal
Buoyancy force is weight of displaced water
Fast flowing water has less pressure than slow water
Pressure is evenly distributed in all directions