G Force

G Force

g-force (with g from gravitational) is a term for accelerations felt as weight and measurable by accelerometers. It is not a force, per se, but a force per unit mass. Since such a force is perceived as a weight, any g-force can be described as a "weight per unit mass" (see the synonym specific weight). The g-force acceleration acts as a multiplier of weight-like forces for every unit of an object's mass, and (save for certain electromagnetic force influences) is the cause of an object's acceleration in relation to free-fall.

This acceleration experienced by an object is due to the vector sum of non-gravitational forces acting on an object free to move. The accelerations that are not produced by gravity are termed proper accelerations, and it is only these that are measured in g-force units. They cause stresses and strains on objects. Because of these strains, large g-forces may be destructive.

Gravitation acting alone does not produce a g-force, even though g-forces are expressed in multiples of the acceleration of a standard gravity. Thus, the standard gravitational acceleration at the Earth's surface produces g-force only indirectly, as a result of resistance to it by mechanical forces. The 1 g-force on an object sitting on the Earth's surface is caused by mechanical force exerted in the upward direction by the ground, keeping the object from going into free-fall. The upward force from the ground ensures that an object at rest on the Earth's surface is accelerating relative to the free-fall condition, which is the path that the object would follow when falling freely toward the Earth's center.

Objects allowed to free-fall in an inertial trajectory under the influence of gravitation-only, feel no g-force. This is demonstrated by the "zero-g" conditions inside a freely falling elevator falling toward the Earth's center (in vacuum), or (to good approximation) conditions inside a spacecraft in Earth orbit. These are examples of coordinate acceleration (a change in velocity) without a sensation of weight. The experience of no g-force (zero-g), however it is produced, is synonymous with weightlessness.

In the absence of gravitational fields, or in directions at right angles to them, proper and coordinate accelerations are the same, and any coordinate acceleration must be produced by a corresponding g-force acceleration. An example here is a rocket in free space, in which simple changes in velocity are produced by the engines, and produce g-forces on the rocket and passengers.

Read more about G Force:  Unit and Measurement, Acceleration and Forces, Human Tolerance of G-force, Short Duration Shock and Jerk, Other Biological Responses To G-force, Typical Examples of G-force, Measuring G-force Using An Accelerometer

Famous quotes containing the word force:

    If you would feel the full force of a tempest, take up your residence on the top of Mount Washington, or at the Highland Light, in Truro.
    Henry David Thoreau (1817–1862)