1C20.10-Penny and Feather in Vacuum Tube

Video: Watch This Demo | Demo #2

UCSC demo video

Description: This demo shows how air affects the motion of objects under gravity.


  • Vacuum pump with tube
  • Penny
  • Feather


  1. Place penny and feather in the tube. Flip the tube 180 degrees and note how they fall.
  2. Turn on the vacuum and check it is evacuating the tube not pressurizing it. (Keep the feather away from where the hose connects to the tube)
  3. Once the gauge on the pump reads zero, turn the switch at the end of the tube 90 degrees to seal the tube. Turn off the pump and remove the hose.
  4. Again, flip the tube 180 degrees to watch the feather and penny fall. Note they fall at the same rate in the absence of air.