1. Student Pressure Post-Lab Questionnaire Supporting Diagrams BU ITOP NS 542 Rhine 2/20/2011

2. 1. Define “vacuum” – can a vacuum exist?  “Horror Vacui” – “Nature Abhors a Vacuum” (Aristotelian view took 2000 years to change)  Galileo, Torricelli, Otto von Guericke, Pascal

3. 2. Student sitting at a desk – sources of pressure?  What about air pressure? Can you feel it? Can you feel changes in air pressure?

4. 3. Define “pressure” – examples

5. 4. Define “fluid” – examples

6. 4 & 5. Define “density” – examples  Density of water = 1 kg/liter = 1 g/cc

7. 6 & 7. Cubic foot of water vs. air  Water 62.4 lbs 62.4 lbs 7.48 gallons 7.48 gallons 28.3 kg 28.3 kg  Air ?

8. 7. How much does a cubic foot of air weigh?  Nothing???  Torricelli Letter, 1644: we live at the bottom of a sea of air 50 miles deep!

9. 8 – 10. Student sitting at a desk at the bottom of a 10 ft deep swimming pool (sharks & suits optional) 10 feet

10. 11. Thin, medium, and wide straws poked into water. Shade in (estimate) the final water level for each straw.

11. 12. Thin, medium, and wide straws poked into water. Pour water into each straw. Shade in (estimate) the final water level for each straw.

12. 13. Medium straw poked into water. You take a sip of water from the tub using the straw.

13. 14. What causes the wind to blow?  Torricelli, 1642: “... winds are produced by differences of air temperature, and hence density, between two regions of the earth.”  Otto Von Guericke made similar observations around 1640 when he was trying to pump all of the air out of wooden barrels – then they cracked and collapsed, air rushed in

14. 15. Poke the medium straw halfway into the water. Put finger on top of straw, and lift it up. What happens and what causes it to happen? Draw a FBD for the water in the straw.

15. 16. Scuba diver is in a pool. Rank the pressure felt by the scuba diver from most to least (use, =). BACEDF

16. 17. Scuba diver is cave diving. Rank the pressure felt by the scuba diver from most to least (use, =). BACEDF

17. 18. Scuba diver in a U-shaped swimming pool. Rank the pressure felt by the scuba diver from most to least (use, =). BACFDGE

18. 19. A scuba diver is in a J-shaped swimming pool (right side of pool sealed on top). Rank the pressure felt by the diver from most to least (use, =). BCFDGEA Capped end. No water in this white area. IH

19. Torricelli’s Mercury Barometer (1643)

20. 20. A scuba diver is in a J-shaped swimming pool (right side of pool sealed on top). What happens if you drill holes in the side at the locations shown? BCFDGEA Capped end. No water in this white area. IH A H G F E