Penny and Feather Falling in a Vacuum


Sketch of the apparatus
Sketch of the apparatus

A penny and a feather fall with same acceleration in a vacuum.



Principles Illustrated

Acceleration due to gravity really is the same for a feather and a penny if there is no air drag!

NCEA & Science Curriculum

SCI 1.1, PHYS 2.4


Feather-and-Penny-SmallWith the penny and feather (or Styrofoam chip) at one end of the air-filled tube, tip the tube quickly up so that the penny and feather fall. The feather will fall slowly due to air drag.

Next evacuate the tube with the pump vented to a fume hood and repeat. The penny and feather will fall together!


The mechanical pump should not be vented to a fume hood as oil droplets are unhealthy. Hold on to the hose when flipping the tube! The hose swings around and can injure someone.

Individual teachers are responsible for safety in their own classes. Even familiar demonstrations should be practised and safety-checked by individual teachers before they are used in a classroom.

Related Resources

  • Video analysis of water rockets with air friction visible in the data. Drop a ball and measure g using Tracker.
  • Video of hammer and feather falling on the moon.

Teaching Resources

Would you like to contribute lesson suggestions? Contact us.


This teaching resource was developed with support from

The MacDiarmid Institute
Faculty of Science, Victoria University of Wellington
School of Chemical and Physical Sciences, Victoria University of Wellington


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