1. Technologies based on the properties of fluids

2. Technologies Based on Density, Buoyancy & Pressure
How could an understanding of the properties of fluids help you go to the deepest spot on the planet?

3. Cartesian Diver Question:
How is the diver able to sink, be suspended and float?
Materials:
bottle with cap
Eyedropper
Water
Procedure
Fill the bottle full of water
Fill the eyedropper about 2/3 full of water.
Put the dropper into the bottle and screw on the cap. Be sure the eyedropper floats before putting on the cap.

4. Squeeze the sides of the bottle and observe what happens.
Release the sides the bottle and observe what happens.
Repeat steps 4 & 5 – this time carefully observe what happens not just to the diver but in the diver.
Make your diver sink, float and hover.
Explain how your diver is able to sink, float and hover; describe properties such as pressure, compression, density and buoyancy.

5. Why does the diver fall? When the bottle is squeezed…
Pressure is put on the water inside the bottle
Pascal’s law
Pressure placed on an enclosed fluid is equal everywhere
Pressure put on the water is also put on the air inside the eyedropper
Air inside the eyedropper is squeezed into a smaller space
Air has same number of particles (mass), takes up less space (volume)
Has greater density
Eye dropper sinks

6. Why does the diver rise? To suspend your diver…
When you release the bottle…
You release the pressure
The air inside the eyedropper is able to expand
Volume of air increases
Density of air decreases
Eye dropper rises
To suspend your diver…
Add enough pressure so that the density of the eyedropper = density of water

7. Submarine
The buoyancy of a submarine can be changed by letting water into / out of the main ballast tanks (MBT)
When the submarine is on the surface, its ballast tanks are full of air
Density of submarine < density of water = floats

8. To dive, submarine releases air and takes on water
Density of submarine > density of water = sinks
To resurface, compressed air is forces into ballast tanks which forces water out
Density of submarine < density of water = float

9. Technologies Based on Solubility
Detergent
Surfactant
Attaches to dirt and oil, separating them from fabric
Suspension agent
Stops dirt from re-attaching to material
Why would different detergents work better on different stains?

10. SCUBA diving
SCUBA = self-contained underwater breathing apparatus
At greater water pressures, more nitrogen gas dissolves in our blood
If a diver ascends slowly – the extra gas leaves the body gradually
If a diver ascends too quickly – the extra gas leaves the body too quickly
Bubbles collect in other body parts and cause considerable pain

11. Solution – Hyperbaric chamber
Increases pressure on body to re-dissolve gas bubbles
Bring pressure back to normal slowly
Allowing the gas to slowly leave the body

12. Technologies Based on Viscosity
Imagine you wan to put air into a basketball or you want to filter the water in your aquarium. What would you use?
Pump
Device that moves a fluid through or into something
Another example?
Heart
Relies on fluids being a certain viscosity

13. Valves Device that controls the flow of fluids Eg. Faucet
Turn one way = open valve = on
Turn other way = close valve = off
Eg. Toilet tank float
When water reaches a certain level – the valve is closed off