The kinematics of a superball bouncing between two vertical surfaces
Brian T. Hefnera)
Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, Washington 98105
~Received 14 October 2002; accepted 6 February 2004!
When a superball is thrown so that it bounces between two horizontal parallel surfaces, the ball will
bounce from both surfaces and then return to the person who threw it. If the surfaces are vertical and
a ball is thrown downward so that it bounces between both surfaces, it also will return to the person
who threw it. In the general case of a superball bouncing between two extended vertical surfaces,
the ball becomes trapped instead of falling and moves up and down the length of the channel with
an oscillation frequency that depends on the ball’s moment of inertia. For this vertical channel the
introduction of a tangential coefficient of restitution produces motion that is similar to both a
damped harmonic oscillator and a falling body. © 2004 American Association of Physics Teachers.
@DOI: 10.1119/1.1701843#