Sponsored by Hawai`i Space Grant Consortium, Hawai`i Institute of Geophysics and Planetology, University of Hawaii, 2001

FIDO THE PING PONG BALL
Created by Dale Olive and Randy Scoville
Future Flight Hawai`i instructors

Demonstration at a glance:
Fido the trained ping pong ball hovers over a hair dryer moving to the left and right with the class and even jumps through the paper towel roll.

Set-up:
The hair dryer needs to be set on high, and cool if you have that setting, while a ping pong ball is placed on the stream of air blowing up. The ball will hang motionless in the stream of air. By tilting the dryer slightly to the left or right the ball can be made to hover at an angle. If a paper towel tube is held over the ball it will suddenly shoot up through it.

Theory:
The Bernoulli principle explains this one too. The faster a fluid moves the lower the pressure it creates. Air speeds up as it moves around the curved surface of the ball much like it does on the curved surface of an airplane wing. This causes a pocket of low pressure around the ball. The higher pressure outside the ball pushes towards and holds the ball in place. Once the tube is placed over the ball and the high pressure is removed, the ball is shot upwards.

Extension:
I do a demo called the "anti-gravity" machine where I hold a balloon over a box and let it go. It hangs motionless which I explain as anti-gravity. All that's in the box is a small fan that is set to blow upwards. There is another version of this demo that is sometimes seen in department stores where a leaf blower holds a beach ball in place over an isle. More power means heavier objects can be suspended in air. Another variation of this demo can be done with a leaf blower and a roll of toilet paper held on a wooden dowel or broomstick handle. By aiming the blower over the roll you create lower pressure above it lifting the paper which begins to unroll rapidly.


Index of Activities.

http://www.soest.hawaii.edu/spacegrant/ScienceDemos/
Communications: Hawaii Space Grant Office
This activity is featured in Future Flight Hawaii, a K-12 Education Project of Hawaii Space Grant Consortium.
FEB 27 2001.