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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 ...
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]
In physics, gravity (from Latin gravitas 'weight' [1]) is a fundamental interaction primarily observed as a 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.
However, the predictions of Newtonian gravity do not match the observations, as discovered in 1859 from observations of Mercury. If the potential energy between the two bodies is not exactly the 1/ r potential of Newton's gravitational law but differs only slightly, then the ellipse of the orbit gradually rotates (among other possible effects).
If we assume a Fatio/Le Sage mechanism for the origin of gravity, the Earth spirals outwards with violation of conservation of energy and of angular momentum. [7] In 1776, Laplace considered a different mechanism whereby gravity is caused by "the impulse of a fluid directed towards the centre of the attracting body".
Objects are falling to the floor because the room is resting on the surface of the Earth and the objects are being pulled down by gravity. Objects are falling to the floor because the room is aboard a rocket in space, which is accelerating at 9.81 m/s 2, the standard gravity on Earth, and is far from any source of gravity. The objects are being ...
Le Sage's theory of gravitation is a kinetic theory of gravity originally proposed by Nicolas Fatio de Duillier in 1690 and later by Georges-Louis Le Sage in 1748. The theory proposed a mechanical explanation for Newton's gravitational force in terms of streams of tiny unseen particles (which Le Sage called ultra-mundane corpuscles) impacting all material objects from all directions.
In 2009, Erik Verlinde proposed a conceptual model that describes gravity as an entropic force. [4] He argues (similar to Jacobson's result) that gravity is a consequence of the "information associated with the positions of material bodies". [5] This model combines the thermodynamic approach to gravity with Gerard 't Hooft's holographic principle.