Coin and Feather Free Fall Tube, Physics Demonstration
by Science Supply Solutions

Simply observation of similar events over the course of a lifetime would lead one to expect that a lighter object, when dropped from the same height as a heavier one, would experience less acceleration than the heavier item. That idea is clearly supported by the heavier object touching down on the ground well before the lighter.

What we’re failing to take into account however, is aerodynamics. The shape of a piece of paper counteracts the influence of gravity, while the shape of a rock doesn’t.

With the free fall tube, we’re able to almost completely eliminate the forces of aerodynamics by evacuating the air from the tube by using a vacuum pump. The end result of this step is that objects, such as the paper and rock, will fall with nearly the exact same acceleration, and reach the bottom of the tube at roughly the same time.

The tube itself is 91.5cm (36″) long, has a diameter of 5.5cm (2.2″) and a circumference of 18cm (7″). A rubber end cap fits into the tube on either side, one of them with a valve to attach the free fall tube to any standard vacuum pump (not included) to evacuate the air.

Also included are a small feather, and a metal disc of approximately the same size and weight as a nickel coin. Other objects can be used in the experiment, though obviously they must be small enough to fit within the tube.