Welcome to You Ask Andy

Anne Vancott, age 11 of Springdale, for her question:

What makes a gyroscope work?

People‑wonder about the motions of a spinning top. How does it balance on tiptoe? If you give it a little push.! how can it try to right itself? Finally, of its own accord why does it wobble and topple over?

The strange power to remain and keep itself upright was in the top only when it was spinning fast. The scientific explanation says that when a wheel or other body is rotating it tends to stay in its plane of rotation. Whew: Let s take those fancy words apart and see what they are made of, Our top was a rotating body ‑ which merely means that it was spinning around. The plane of rotation is an extention of the axis, the line in the center ground which the top spins.

The plane of rotation in our spinning top was straight up and down because that was the position of the top when we set it spinning. So long as it rotates fast it stays up and down and oven tries to ‑,‑et back into that position when pushed. But soon it uses up all the energy we gave it. The rotation slows down, loses its magic power and the top wobbles and topples. If the top had a little motor to keep it spinning it would remain o n tiptoe.

Men knew and perhaps wondered about the strange antics of a spinning top for countless a‑es. Not until 1851, did a Frenchman named Leon Fouchault figure out the strange power in a rotating body and the next year he used this principle to make the first gyroscope. But the first gyroscopes were just curios. Then an American named Elmer Sperry saw that the axis of a rotating body could be used as a very reliAble pointing finger. In 1911 he patented a compass based on a gyroscope. Nowadays, the gyroscope is used to steer great ships, correct their rolling and adjust their balances. It is used in planes and rockets and it is a vital part of the great missiles getting ready to take, off into space.

Some of the up‑to‑date, gyroscopes are large and complex and some are fixed to control other instruments. But the heart of any gyroscope is always a rotating wheel. In a complex instrument, this wheel is kept turning continuously by a power‑driven motor. You can see somewhat how it operates with a simple toy gyroscope which is set spinning with a bit of string.

The toy gyroscope is a metal disk with a thick rim. It has an axis which extends out to link it with an outer ring of metal. The axis works on bearings and extends through the outer ring to a little ball at each end. Wind the string around one of these balls and perk it away fast. This gives the spin which sets the gyroscope rotating. You may now move it, tip it, turn it or make it dance on a string. The rotating wheel will stay on its plane of rotation,

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