The PhiTOP

USD$ 19.95

Makes a perfect gift, desktop display piece, or student stumper.

64 in stock


We’ve fallen in love with the PhiTOP, and bet you will, too! This beautifully crafted top does for angular momentum what Newton’s Cradle does for linear momentum. When spun, it starts out horizontal and then, surprisingly, stands upright. Wow! In the process, it illustrates the difference between equilibrium and stability. The rise of the “center of mass” is a fascinating physics problem. It will spin for minutes on end, producing a marvelous optical illusion as it slows down. Invented by astrophysicist Kenneth Brecher, the PhiTOP encourages exploration of force, mass, density, gravity, friction, and time. In short, the PhiTOP is an elegant scientific, mathematical, and aesthetically-pleasing object that makes a perfect gift, desktop display piece, or student stumper. See for yourself in our video! Egg is ~5 cm tall (2″).

Bring a refrigerator magnet next to a PhiTOP that is made from a non-magnetic metal such as aluminum or brass while it is spinning and it will slow down and stop. This is a simple demonstration of the magnetic induction principle that underlies Nikola Tesla’s famous 19th century Egg of Columbus demonstration that led directly to the acceptance of AC electricity over DC. The original 19th century apparatus employed a rotating 3-phase magnetic field configuration with no moving parts to spin up a copper egg shaped object.

Additional information

Weight 0.33 lbs
Age Range



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