Centrifugal Eggbeater
centrifugal force - planetary rotation - equatorial bulge
What it shows:
The rotation of a planet about its axis causes its equator to bulge due to the centrifugal force acting on its
mass. Here a spinning wire frame simulates the effect.
How it works:
Planets are actually oblate spheroids rather than spheres due to their rotation. This device consists of two
spring metal rings mounted on a metal axis. The north pole is free to slide so that, as the frame spins, the hoops
flatten and the equator bulges. The axis is hand cranked using a 9-1 gear ratio; a moderate turn of the handle
flattens the hoops to half the polar diameter.
figure 1. Centrifugal Eggbeater (crank and C-clamp not shown)
Setting it up:
The assembly clamps to the edge of a bench.
Comments:
This effect causes the equatorial radius of the Earth to be 43km greater than its polar radius. The effect is more
pronounced for Jupiter, whose rotation period is under 10 hours. Jupiter's equatorial radius is 71492km, 4638km
greater than its polar, giving the planet a distinctly flattened appearance. Our machine seems to be of Russian
origin, but Cenco (74435) make essentially the same thing. Rating ***