Why are gyroscopes stable

You could not be signed in, please check and try again. Sign in with your library card Please enter your library card number. Show Summary Details Overview gyroscopic stability. View all related items in Oxford Reference » Search for: 'gyroscopic stability' in Oxford Reference ».

All rights reserved. Sign in to annotate. Delete Cancel Save. Cancel Save. Here are two explanations, including one that doesn't rely on any knowledge of the gyroscopic effect. See which you prefer.

One thing's for sure, anything to do with the gyroscopic effect is counterintuitive! Explanation A: What stops a spinning top from falling over? A spinning top is governed by the gyroscopic effect. The faster a gyroscope spins, the bigger the gyroscopic effect - ie the more resistant the gyroscope is to any disturbing couple. For the top, gravity acts down through its centre blue arrow in the picture above , and an equal force acts up where the tip sits on the table black arrow 5.

If the top is tilted then these two forces are not opposite each other, as in the picture, so generating a couple. This couple is fixed, independent of how fast the top spins so with paragraph 3. A couple is just any pair of equal-and-nearly-opposite forces that act to twist something around. Gyroscopic effect: 7. A spinning rotor has an axis of spin.

A couple acting about this axis can only ever change the spinning speed 9. To change the direction of the axis of spin the only remaining possibility is to apply a couple at right angles to the spinning axis. The axis of spin will deviate so as to direct its spin in the direction of the applied couple. Another noticeable property of them, if you've ever held one, is that it will try to resist attempts to move its position.

You can even tilt it at an angle when suspended from a stand, and it will appear to levitate, albeit whilst orbiting the stand. Even more impressively, you can lift up a gyroscope with a piece of string around one end. The explanation for this phenomenon is tricky to understand intuitively. Their ability to seemingly defy gravity is a product of angular momentum , influenced by torque on a disc, like gravity, to produce a gyroscopic precession of the spinning disc or wheel. This phenomenon is also known as gyroscopic motion or gyroscopic force, and it has proved to be very useful indeed for us humans.

These terms refer to the tendency of a rotating object, not just a gyroscope, to maintain the orientation of its rotation. As such, the rotating object possesses angular momentum, as previously mentioned, and this must be conserved.

Because of this, t he spinning object will tend to resist any change in its axis of rotation, as a change in orientation will result in a change in angular momentum.

Another great example of precession occurs with the planet Earth too. As you know, the Earth's rotational axis actually lies at an angle from the vertical which, owing to its angle, traces a circle as the rotational axis itself rotates. While not entirely relevant to this article, the reason for Earth's odd tilt is actually pretty interesting.

This effect is enhanced the faster the disc or wheel is spinning, as Newton's Second Law predicts. This seems pretty obvious to anyone with a basic knowledge of physics. The main reason they seem to defy gravity is the effective torque applied to the spinning disc has on its angular momentum vector. The influence of gravity on the plane of the spinning disc causes the rotational axis to "deflect".

This results in the entire rotational axis finding a "middle ground" between the influence of gravity and its own angular momentum vector. Now, factoring in the fact that the gyroscope is being stopped from falling towards the center of gravity by something in the way leads to the fascinating properties we see in these devices. A picture -- well video -- is worth a thousand words, so we'll delegate a more in-depth explanation to the following video:. In order to fully answer this question, we need to assess how each device works.

Since we have already covered the gyroscope in some detail above, let's check out what an accelerometer is and how it works. An accelerometer is defined by the Merriam Webster dictionary as " an instrument for measuring acceleration or for detecting and measuring vibrations.

Great, but that doesn't really give us much information. Accelerometers , in their most basic sense, are electromechanical devices that measure acceleration forces -- hence the name. These forces can be either static like gravity or dynamic caused by moving or vibrating the device. There are various ways to make an accelerometer with most using either the piezoelectric effect or through sensing capacitance. The former tend to consist of microscopic crystal structures that become stressed by accelerative forces and generate a voltage in return.

The latter makes use of two microstructures placed next to one another. Each has a certain capacitance, and as accelerative forces move one of the structures, its capacitance will be changed.

By a dding some circuitry to convert from capacitance to voltage, and you will get a very useful little accelerometer. There are even more methods, including the use of the piezoresistive effect, hot air bubbles, and light, to name but a few. So, as you can see, accelerometers and gyroscopes are very different beasts indeed. In essence, the main difference between the two is that one can sense rotation, whereas the other cannot.

Since gyroscopes work through the principle of angular momentum, they are perfect for helping indicate an object's orientation in space. Accelerometers, on the other hand, are only able to measure linear acceleration based on vibration. However, there are some variations of accelerometer that do also incorporate a gyroscope. These devices consist of a gyroscope with a weight on one of its axes. The device will react to a force generated by the weight when it is accelerated by integrating that force to produce velocity.