where can I get the feather coin experiment ?

jtobako8 years ago
has one...not sure how well it works for the price, and looks like it needs more parts like a vacuum pump.
ewilhelm8 years ago
Full Instructable here:
Guinea and Feather Experiment.

I think you might be referring to a demonstration that takes place in an evacuated tube to show that gravitational acceleration does not depend on weight.

Creating a good vacuum cheaply is not easy, but possible:
But instead of trying to create a vacuum, why not just control for the effects of air resistance? Drop a tennis ball from the top of a building, once empty, and another time filled with pennies.