Gyroscopes

In Germany 1817, German astronomer Johann Bohnenberger created, the first device that resembled what we know as a gyroscope today. He called it ‘The Machine’, but unlike today’s gyroscopes, which run on a disc, The Machine was based on a massive rotating sphere. It was fifteen years later that the American Walter R. Johnson created a similar device to The Machine using a disc like today’s gyroscopes.

When the famous French mathematician Pierre-Simon Laplace (known for Laplace’s equation, Laplace transform, Bayesian interpretation etc.,) found out about it he recommended it as a teaching aid, and so it came to the attention of the French physicist, Leon Foucault. It was Leon Foucault who named the gyroscope during an experiment to view the Earth’s rotation. The Greek for ‘to see’ is ‘skopeein’ and the Greek for ‘rotation’ is ‘gyros’, hence Gyroscope (gyros – skopeein). During this experiment the Earth’s rotation was viewed for between 8 and 10 minutes.

Today, you can find gyroscopes everywhere; from rockets to smart phones, to Star Wars! Yes, even during the filming of the original Return of the Jedi in 1983 gyroscopes were present! During the speeder chase on the moon of Endor gyroscopes were used in a Steadicam rig that allowed the cameraman to move across terrain without causing the video itself to look shaky. This was due to the gyroscopes in the rig stabilising the shot. Because the film looked so smooth the speeders really looked like they were flying! 

On the opposite side of the spectrum, we have control moment gyroscopes (CMG) that are used in some spacecraft, these are comprised of a spinning rotor and motorized gimbals that tilt the rotor’s angular momentum, this causes a gyroscopic torque, in turn rotating the spacecraft. How does this work? Well, imagine the gyroscope is rotating clockwise. As there is no external torque acting on the spacecraft and gyroscope (why would there be, they are floating in space after all!) the angular momentum of the combined system (gyroscope and spacecraft) must remain zero according to the law of conservation of angular momentum. But since the gyroscope is rotating clockwise, it is the spacecraft that must rotate anti-clockwise to ensure the total angular momentum of the isolated system remains 0. If the total angular momentum of the system didn’t remain 0 despite nothing moving the spacecraft-gyroscope system, then energy would be being created out of nothing and that would probably break physics!

Now you may be thinking: what are Gimbals? Well, a gimbal is basically a circle that is mounted around an object that allows said object to rotate on a single axis e.g. a flat disc could spin horizontally and because it is supported by gimbals it wouldn’t spin in any other direction than horizontally. This is where gyroscopes come in. A gyroscope is a spinning wheel or disc (like in the above example) whose orientation is not directly affected by outside factors. This is because there are 3 gimbals mounted around the disc that give the gyroscope freedom of rotation in all 3 dimensions, so if you attached a handle to it and ran up and down the stairs you would notice the disc in the middle stayed in the exact same orientation the entire time!

Gyroscopes in smart phones help the phone understand which way it is orientated, if you play a game that requires you to tilt your phone to move (like driving car games), the gyroscope is used to sense the motion you create. Gyroscopes in smart phones don’t actually use discs with gimbals around them. They use MEMS gyroscopes.

In summary, you most likely don’t spend your day without using a gyroscope and yet you wont even know it! They are one of the most useful inventions of all time and they will continue to be useful for future scientific endeavours.

There are numerous experiments you can do with a gyroscope. We have compiled a few below;

          Experimental Question: What happens when a gyroscope is placed on a thin string? 

Materials: A piece of string, a gyroscope

Before trying the experiment, think about what will happen to the gyroscope once set in motion on the string. Will it immediately fall off?

 

 Experimental Question: What happens when you juggle a gyroscope between your hands? 

Materials: gyroscope

Try setting the gyroscope in motion and placing it on your palm, then juggle it to your other palm. Will it keep its balance?

Have fun!

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