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In physics, gravity (from Latin gravitas 'weight' [1]) is a fundamental interaction primarily observed as mutual attraction between all things that have mass.Gravity is, by far, the weakest of the four fundamental interactions, approximately 10 38 times weaker than the strong interaction, 10 36 times weaker than the electromagnetic force and 10 29 times weaker than the weak interaction.
Before Newton’s law of gravity, there were many theories explaining gravity. Philoshophers made observations about things falling down − and developed theories why they do – as early as Aristotle who thought that rocks fall to the ground because seeking the ground was an essential part of their nature. [6]
The gravity g′ at depth d is given by g′ = g(1 − d/R) where g is acceleration due to gravity on the surface of the Earth, d is depth and R is the radius of the Earth. If the density decreased linearly with increasing radius from a density ρ 0 at the center to ρ 1 at the surface, then ρ ( r ) = ρ 0 − ( ρ 0 − ρ 1 ) r / R , and the ...
Examples of force. The following list shows different orders of magnitude of force. Since weight under gravity is a force, several of these examples refer to the weight of various objects. Unless otherwise stated, these are weights under average Earth gravity at sea level.
If gravity is the only influence acting, then the acceleration [3] is always downward and has the same magnitude for all bodies, commonly denoted . Since all objects fall at the same rate in the absence of other forces, objects and people will experience weightlessness in these situations. Examples of objects not in free-fall:
Newton's laws are often stated in terms of point or particle masses, that is, bodies whose volume is negligible. This is a reasonable approximation for real bodies when the motion of internal parts can be neglected, and when the separation between bodies is much larger than the size of each.
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 most familiar non-contact force is gravity, which confers weight. [1] In contrast, a contact force is a force which acts on an object coming physically in contact with it. [1] All four known fundamental interactions are non-contact forces: [2] Gravity, the force of attraction that exists among all bodies that have mass. The force exerted on ...