Also known as the Guineaand feather experiment. An economical version of a classic device! It demonstrates that all objects experience the same gravitational acceleration and fall at the same speed in a vacuum, but in air the air resistance slows down some objects more than others. Features a disc and a feather in a tough, clear, plastic tube, 90 cm long and 4.5 cm diameter, with rubber end caps and hose cock for connection to any standard vacuum pump (not included). Includes activity guide.