Technologies based on the properties of fluids

1. Technologies based onthe 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? • 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