Physics Demo Number: 198				Approximate Run Time: 15min
Coin and Feather TubeÂ
Demo Description Use a dedicated  plastic chamber with three objects inside:      (1)a coin clothed in pink tubular Nylon climbing  webbing (2) a  small square of yellow silk  and (3) a round piece of white  printer paper. The chamber is constructed to easily allow the air to be removed by a vacuum pump.			Â	Scientific Principles  An evacuated tube shows identical free fall behavior for three objects that fall quite differently in air.
Equipment   Tube with vacuum attachment on an o-ring fitted end. Internal pink-clothed  quarter dollar and a small patch of yellow  silk and a small piece of white paper.     Â	Â	Equipment Location [D-4-1] Â
Instructions  The photo shows the tube with the pink-clothed quarter dollar and  a yellow silk patch resting inside a little to the right of  the tubes longitudinal center. Not seen in the photo is the white scrap of paper. The second photo shows the pump used to remove air from the tube. The two lighter objects take longer to reach the bottom when there is air in the tube.   It was determined that styrofoam packing peanuts are not very suitable for feather replacement, since they out-gas and then are crushed down to a large density when air is let back into the tube.  Hence the piece of yellow silk for a feather replacement. The pink jacket was necessary for the quarter to keep if from bouncing off the bottom surface of the tube and confusing perceptions of relative arrival times. Â
        Writeup created by David A.  Burba Copyright © 2014, Vanderbilt University.   All Rights Reserved.