Code Number:1D50.33
Demo Title: Central Forces - Carry a Ball
Condition: Excellent
Principle: Forces Due To Circular Motion
Area of Study: Mechanics
Equipment:
Wine Glass, Small Cork Ball, or Rubber Ball.
Procedure:
These wine glasses are also used for the 3D40.50 - Musical Goblet or Bowl demonstration.
To carry a ball without touching it you need a wine glass with a body that has a slightly larger diameter than the rim. Invert it an place it over the ball, and then move the wine glass in a circle. The ball will start to rotate around the rim inside the wine glass and then will climb up into the body of the glass. Continue the rotational motion of the glass and you can carry the ball anywhere you wish.
References:
- R. D. Edge, "Levitating a Marble", TPT, Vol. 24, #5, May 1986, p. 295.
- "M-370: Lift Ball in Bottomless Cup", DICK and RAE Physics Demo Notebook.
- Robert Ehrlich, "G.3, Rotating a Ball Inside an Inverted Plastic Cup", Turn the World Inside Out, p. 91 - 92.
- Martin Gardner, "Transporting an Olive", Science Tricks, p. 44.
- Bobby Mercer, "Jar Spin", Junk Drawer Physics, IBSN 978-1-61374-920-3, p. 9 - 10.
University of Maryland Physics Department QOTW Question #166
University of Maryland Physics Department QOTW Answer #166