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The standard acceleration of gravity or standard acceleration of free fall, often called simply standard gravity and denoted by ɡ 0 or ɡ n, is the nominal gravitational acceleration of an object in a vacuum near the surface of the Earth. It is a constant defined by standard as 9.806 65 m/s 2 (about 32.174 05 ft/s 2).
The gravitational constant is a physical constant that is difficult to measure with high accuracy. [7] This is because the gravitational force is an extremely weak force as compared to other fundamental forces at the laboratory scale. [d] In SI units, the CODATA-recommended value of the gravitational constant is: [1]
fine-structure constant: 0.007 297 352 5643 (11) 1.6 ... While the values of the physical constants are independent of the system of units in use, each uncertainty as ...
The agreed-upon value for standard gravity is 9.80665 m/s 2 (32.1740 ft/s 2) by definition. [4] This quantity is denoted variously as g n, g e (though this sometimes means the normal gravity at the equator, 9.7803267715 m/s 2 (32.087686258 ft/s 2)), [5] g 0, or simply g (which is also used for the variable local value).
A conventional standard value is defined exactly as 9.80665 m/s² (about 32.1740 ft/s²). Locations of significant variation from this value are known as gravity anomalies . This does not take into account other effects, such as buoyancy or drag.
Acceleration has the dimensions of velocity (L/T) divided by time, i.e. L T −2. The SI unit of acceleration is the metre per second squared (m s −2); or "metre per second per second", as the velocity in metres per second changes by the acceleration value, every second.
In the case of an increase in speed from 0 to v with constant acceleration within a distance of s this acceleration is v 2 /(2s). Preparing an object for g-tolerance (not getting damaged when subjected to a high g-force) is called g-hardening. [citation needed] This may apply to, e.g., instruments in a projectile shot by a gun.
A physical constant, sometimes fundamental physical constant or universal constant, is a physical quantity that cannot be explained by a theory and therefore must be measured experimentally. It is distinct from a mathematical constant , which has a fixed numerical value, but does not directly involve any physical measurement.