# How Gyroscopes Work

Discussion in 'Mechanical | Automobile | Aeronautics' started by CE Designer, Feb 24, 2012.

### CE DesignerAce

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### CE DesignerAce

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No takes on this?

### A.V.RamaniMentor

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I had a German (Roman Catholic Priest) science teacher in high school.He had brought with him gyroscopes, which fascinated me and I spent many days working with them.

Simply put, the principle of a gyroscope is that the direction of the axis of spin of a rotating mass is invariant in space. We are living on one gyroscope called the earth. Its axis always points to the pole star even as it orbits around the sun.

My son brought this toy Levitron from the US considering me about 5 year old. I have lots of fun with this.
http://www.levitron.com/
http://www.gyroscopes.org/

### CE DesignerAce

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Ok, so if the earth acts like a gyroscope then how come they say the earth was thrown off its axis when there was that earthquake in the Indian Ocean that caused the tsunami. Won't it (the earth) be pulled back on its original axis? Or were they referring to a momentary tilt when they said that?

### IssueStar

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Well, if I am not wrong, then earth behaves like a Gyroscope. But how can we support the fact that the inclination of earth's axis is changing? Is it because of slowing of earth's rotational speed?

### A.V.RamaniMentor

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If you see the video you can see the gyro with the end of one axis on a central pivot. When it is spinning it stays on the single pivot . However, it also rotates on a horizontal plane around the pivot. A gyro has an invariant direction in space of its axis of rootation only when no force acts on the axis. When a force is applied (in this case the weight of the gyro since it is unsupported at the other end) the axis will move in a direction perpendicular to the applied force. This is why the gyro is rotating around the central pivot.

There is more to this. The direction of this precession force is related to the spin direction (clockwise or anti clockwise) of the gyro. If the spin direction is reversed, so also the direction of rotation on the pivot.

If a powerful earth quake erupts at a high enogh latitude, a huge torque is applied trying to change the orientation of the North-South axis, this will set up a precession force perpendicular to both the axis and the direction of application of the force. This causes the shift. Once the quake stops, the shift also stops. Whatever shift happenned is permanent since there is no restoring force, since you cannot set up another earthquake of equal magnitude precisely 180 degrees apart.

The house fly has the most irritating habit of landing on your nose tip or forehead. When brushed off it flies off but lands precisely back on the nose tip a bit later. Under its wings it has a vibrating reed like appendage, which acts like a gyroscope. Like a gyro compass on an air craft, this vibratory gyro tells the fly precisely where your nose is so that it can come back.

Gyros are everywhere in nature - from spinning galaxies to a buzzing fly.

@Issue: [But how can we support the fact that the inclination of earth's axis is changing?]
Earth is not a perfectly balanced fly wheel. Small imbalances an lead to a slow long term change.
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### CE DesignerAce

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Bravo, I understand CEans' explanation better, its like we have our own language

### A.V.RamaniMentor

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### suryanApprentice

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### IssueStar

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### IssueStar

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