Inertia Demonstrator, 1 Each

The Inertia Demonstrator by United Scientific is a desk-top apparatus for the classic card-and-ball experiment on Newton's first law. A spring-loaded piston strikes a thin metal card out from under a steel ball, which stays on its pillar, while a slow pull on the cord shows the opposite result. The card is tethered to the aluminum base. Physics teachers use it for repeatable inertia demonstrations.