RAINBOW launches five small balls into five rubber cups with amazing
accuracy. The exhibit employs a steel raceway, whose angle can be
adjusted up or down, to vary the distance each ball travels. A catch
mechanism holds each ball in place alone the rail; when the catch
is released all the balls are launched off the end of the rail.
The balls that are the highest go out the farthest, but regardless
of the speed at which it is launched, each ball falls in a parabolic
arch (thus the name "Gravity's Rainbow.") If the rubber
cups are set in the proper positions they catch each ball, proving
that the arc of each ball is predictable. It is possible to move
the launch point of each of the five balls and the position of each
of the five cups. One can experiment with all elements of the exhibit:
the angle of the rail, the number of balls, and the launch and landing
points of the balls. A clever net assembly catches dropped balls
and provides a place to keep spare balls.