50. Guinea and Feather Tube

A coin and feather (or rubber cork and styrofoam chip) are inside a lucite tube 1.5 m long. When the tube is switched end for end, the rate of falling of the two objects can be compared. The tube is then evacuated to show that they fall at the same rate in a vacuum.

This experiment was repeated on the moon by Apollo 15 astronauts using a feather and a hammer. You can see the NASA video here. We also have this clip on video disk which can be played in class.