T. Killian
K. Langley
T. Truscott
Department of Mechanical Engineering
Brigham Young University

When a ball is dropped into a puddle, the rebound height is suppressed by the exchange of a portion of the rebound momentum into fluid motion. Upon impact with the water, a radial jet and splash curtain are formed as fluid is instantaneously displaced by the falling ball. As the ball rises, the splash curtain is drawn in and a column of fluid is drawn upward behind the ball. The formation of the fluid column is another manifestation of this beautiful energy exchange.

Finally, when the gravitational force acting on the volume of fluid drawn in the column overcomes the energy of the ball's inertia, the fluid column pinches off close to the ball and falls back into the pool as the now unrestrained ball is free to rise and utilize the remainder of its kinetic energy. These images depict this energy exchange with a ping pong ball falling into a shallow pool of water.

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This image can be freely reproduced with the accompanying credit: "Department of Mechanical Engineering, Brigham Young University. Authors: T. Killian, K. Langley, T. Truscott".