Mg-1 Guinea and Feather Apparatus


To show that bodies of different mass accelerate equally under gravity.


  • Rotary Vacuum pump
  • Guinea and feather apparatus (as in diagram)

Guinea and Feather Guinea and Feather Diagram

Guinea and Feather Apparatus and Diagram.


A glass tube approximately one metre in length containing a lead slug and a feather is attached to an evacuating pump. The accelerations of the objects in the tube under gravity can be observed before and after evacuation.

Thirty seconds of evacuation is sufficient for a convincing demonstration.