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Gravitaxis (or geotaxis [1]) is a form of taxis characterized by the directional movement of an organism in response to gravity. [2] There are a few different causes for gravitaxis. Many microorganisms have receptors like statocysts that allow them to sense the direction of gravity and to adjust their orientation accordingly. However ...
The force of gravity on the surface of the Earth, normally denoted g, has remained constant in both direction and magnitude since the formation of the planet. [citation needed] As a result, both plant and animal life have evolved to rely upon and cope with it in various ways. For example, humans employ internal models in motor planning that ...
Gravitropism (also known as geotropism) is a coordinated process of differential growth by a plant in response to gravity pulling on it. It also occurs in fungi. Gravity can be either "artificial gravity" [clarification needed] or natural gravity. It is a general feature of all higher and many lower plants as well as other organisms.
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]
Gravitation also explains astronomical phenomena on more modest scales, such as planetary orbits, as well as everyday experience: objects fall; heavy objects act as if they were glued to the ground, and animals can only jump so high. Gravitation was the first interaction to be described mathematically.
The 12th-century scholar Al-Khazini suggested that the gravity an object contains varies depending on its distance from the centre of the universe (referring to the centre of the Earth). Al-Biruni and Al-Khazini studied the theory of the centre of gravity, and generalized and applied it to three-dimensional bodies.
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 ...
For two pairwise interacting point particles, the gravitational potential energy is the work that an outside agent must do in order to quasi-statically bring the masses together (which is therefore, exactly opposite the work done by the gravitational field on the masses): = = where is the displacement vector of the mass, is gravitational force acting on it and denotes scalar product.