Guinea and Feather (1C20.10)

Description:

Two clear acrylic tubes contain a piece of paper and an aluminum disc. Times of fall for the paper and aluminum disc are compared when the tubes are at atmospheric pressure and when they are evacuated.

Procedure or Operation Notes:

1) In the picture below, all three valves are open when the toggle levers are perpendicular to the valve body. The tubes are at atmospheric pressure and the demo can be performed with air resistance.

2) Attach the vacuum hose to the hose barb and start the vacuum pump.

3) When the gauge reads close to -76 cmHg, close all three valves so the toggle lever is parallel to the valve body.

4) Turn off the pump and remove the vacuum hose from the hose barb. Repeat the demo a few times at reduced pressure.

5) Open the valves to let air rush back in, and repeat the demo one more time at atmospheric pressure.

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References, Comments, or Footnotes:

1) Heavy Boots: An apocryphal and humorous story about gravity discussed in a philosophy course.

2) An archive of SolidWorks CAD files is available.