How a Gyroscope Works

Gyroscopes Mkhblink The gyroscope, with its intricate and puzzling movements, was invented by Jean Benard Focault to show also the earth's motion around its axis. What it is exactly is any rotating body that exhibits two fundamental properties: gyroscopic inertia (rigidity in space) and precession (the tilting of the axis at ninety degree angles to any force inclined to alter the plane of rotation). These properties are present in all rotating bodies including planetary bodies like the earth, moon and sun.

The term gyroscope is usually in reference to a spherical, wheel-shaped object that is universally mounted to be free to rotate in any direction. Gyroscopes are used to demonstrate the two properties of rotating bodies or to indicate movements in space. Gyroscopic Inertia can be explained using Newton's first law of motion, which states that a body tends to continue in its state of rest or uniform motion unless it is subject to some outside force.

So the wheel of a gyroscope, once in motion, tends to rotate continuously in the same plane about the same axis in space like the Earth will continue to rotate around the sun, unless it is disturbed by an outside force or torque. Precession is observed when a force applied to a gyroscope changes the direction of the axis of rotation, the axis will move in a direction at right angles to the direction in which the force is applied.

The force produced by the angular momentum of the rotating body and the applied force results in this processional motion. Gyroscopes are used in aircraft, ships, submarines, rockets and in many other auto-navigation type vehicles. Gyroscopes utilize torque. Torque is the angular version of force. The units for torque are in Newton-meters. Torque is observed when a force is exerted on a rigid object pivoted about an axis and. This results in the object rotating around that axis.

It is easier to understand what happens when holding a gyroscope if it is compared to the less complex linear momentum because they are similar in many ways. "Linear momentum is the product of an object's mass and its instantaneous velocity. The angular momentum of a rotating object is given by the product of its angular velocity and its moment of inertia.

Just as a moving object's inertial mass is a measure of its resistance to linear acceleration, a rotating object's moment of inertia is a measure of its resistance to angular acceleration" (Serway 325). Factors which effect a rotating object's moment of inertia are its mass and on the distribution of the objects mass about the axis of rotation.

A small object with a mass concentrated very close to its axis of rotation will have a small moment of inertia and it will be fairly easy to spin it with a certain angular velocity. However if a gyroscope of equal mass, with its mass more spread out from the axis of rotation, will have a greater moment of inertia and will be harder to accelerate to the same angular velocity (Martindale 320). Similar to the Law of Conservation of Linear Momentum is the Law of Conservation of Angular Momentum.

This law applies to rotating systems, such as gyroscopes, that have no external torques or moments applied to them. This law helps to explain why a rotating object will start to spin faster (with a greater angular velocity) if all or some of its mass is brought inward towards its rotating axis or why it would start to rotate with a decreased angular velocity if some of its mass is spread out away from its rotating axis.

An example of this is the slowly spinning figure skater that pulls his arms close to himself and suddenly speeds up his angular velocity. When he wants to decrease his angular velocity (or his velocity of rims) he merely spreads out his arms again and just as suddenly as he sped up, he can slow down. So what exactly can gyroscopes be used for in everyday life? The general effect of a gyroscope is, after all, that once you spin it, the axis will point in the same direction indefinitely.

A gyro-compass uses this idea by mounting a gyroscope in a set of gimbals sot that it will point the same direction continuously. It also works with an INS, in which sensors mounted on the gimbals' axles will detect when the platform actually rotates. The INS then processes those signals to understand how the vehicle's rotations are relative to the platform.

When a set of three sensitive accelerometers are added to the platform, it is capable of detecting exactly where the vehicle is going and how its motion is being affected and changing in all three directions. This is the principle behind an airplane's autopilot feature, where the plane is kept on course. It is also the way in which a rocket's guidance system can send a rocket into a specific orbit (Brain 1). Basically, a gyroscope is a universally mounted spinning wheel.

One of the fundamental properties that the spinning axis utilizes is that it tends to remain in a fixed space property known as rigidity. This is the central principle in which automatic pilots are founded on. Any movement of the airplane around one of its three axes will move the case of the gyroscope, but won't affect the position of the spinning axis. This relative movement between gyro and case is employed to produce unbalanced air.