Happy-Sad Balls (Classroom set of 8)

The Happy ball is common neoprene and rebounds very well. The Unhappy ball is norborene polymer rubber and possesses excellent impact absorption properties which allow it to hit the floor like a rock. Although both balls are identical in shape, the Unhappy ball has a bounce of almost zero while the Happy ball rebounds very well under standard 10-30°C conditions. These balls are useful for demonstrating a variety of topics such as polymers, density, and elastic vs inelastic collisions.