Email Print Facebook Reddit Twitter. This entry was posted in -- By the Physicist , Physics. Bookmark the permalink. Potato says:. December 22, at pm. Henchman says:. April 14, at am. The Physicist says:. April 14, at pm. Fazreen Hamidi says:. January 24, at pm. HEY, may I know whether gyroscope helps to keep the bicycle moving forward?
Nestico Ecarlo says:. February 21, at am. But there is no such thing as a perfect top.. Gravity is a property of ambient conditions. Ryspek Usubamatov says:. August 21, at am. Sinisa says:. October 8, at pm. Nestico Ecarlo: Great explanation, very intuitive, without need to invoke conservation laws. Leave a Reply Cancel reply Your email address will not be published.
Comment Name Email Website Notify me of follow-up comments by email. Send your questions about math, physics, or anything else you can think of to:. Search for:. By: Marshall Brain. Gyroscopes can be very perplexing objects because they move in peculiar ways and even seem to defy gravity. A typical airplane uses about a dozen gyroscopes in everything from its compass to its autopilot. The Russian Mir space station used 11 gyroscopes to keep its orientation to the sun , and the Hubble Space Telescope has a batch of navigational gyros as well.
Gyroscopic effects are also central to things like yo-yos and Frisbees! In this edition of HowStuffWorks , we will look at gyroscopes to understand why they are so useful in so many different places.
You will also come to see the reason behind their very odd behavior! If you have ever played with toy gyroscopes, you know that they can perform all sorts of interesting tricks.
They can balance on string or a finger; they can resist motion about the spin axis in very odd ways; but the most interesting effect is called precession. This is the gravity-defying part of a gyroscope. The following video shows you the effects of precession using a bicycle wheel as a gyro:. The most amazing section of the video, and also the thing that is unbelievable about gyroscopes, is the part where the gyroscopic bicycle wheel is able to hang in the air like this:. This mysterious effect is precession.
In the general case, precession works like this: If you have a spinning gyroscope and you try to rotate its spin axis, the gyroscope will instead try to rotate about an axis at right angles to your force axis, like this:. Why should a gyroscope display this behavior? It seems totally nonsensical that the bicycle wheel's axle can hang in the air like that. If you think about what is actually happening to the different sections of the gyroscope as it rotates, however, you can see that this behavior is completely normal!
Let's look at two small sections of the gyroscope as it is rotating -- the top and the bottom, like this:. When the force is applied to the axle, the section at the top of the gyroscope will try to move to the left, and the section at the bottom of the gyroscope will try to move to the right, as shown.
If the gyroscope is not spinning, then the wheel flops over, as shown in the video on the previous page. If the gyroscope is spinning, think about what happens to these two sections of the gyroscope: Newton's first law of motion states that a body in motion continues to move at a constant speed along a straight line unless acted upon by an unbalanced force. 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. Another form of the gyroscope is an optical gyroscope. This device has no moving parts and is commonly used in modern commercial jetliners, booster rockets, and orbiting satellites.
Taking advantage of something called the Sagnac effect , these devices use beams of light to provide a similar function to mechanical gyroscopes. The effect was first demonstrated in by Franz Harris, but it was French scientist Georges Sagnac who correctly identified the cause. I f a beam of light is split and sent in two opposite directions around a closed path on a revolving platform with mirrors on its perimeter, and then the beams are recombined, they will exhibit interference effects.
In , Sagnac concluded that light propagates at a speed independent of the speed of the source. He also discovered that despite the beams both being within a closed-loop, the beam traveling in the same direction of rotation arrived at its starting point slightly later than the other one. To do this, take your right hand and make a right angle. Then you can stretch your fingers out along the radius of the wheel.
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