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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.
Newton's law of gravitation resembles Coulomb's law of electrical forces, which is used to calculate the magnitude of the electrical force arising between two charged bodies. Both are inverse-square laws, where force is inversely proportional to the square of the distance between the bodies. Coulomb's law has charge in place of mass and a ...
The pound-force has a metric counterpart, less commonly used than the newton: the kilogram-force (kgf) (sometimes kilopond), is the force exerted by standard gravity on one kilogram of mass. The kilogram-force leads to an alternate, but rarely used unit of mass: the metric slug (sometimes mug or hyl) is that mass that accelerates at 1 m·s −2 ...
This acrobatic airplane is pulling up in a +g maneuver; the pilot is experiencing several g's of inertial acceleration in addition to the force of gravity. The cumulative vertical axis forces acting upon his body make him momentarily 'weigh' many times more than normal. In an airplane, the pilot's seat can be thought of as the hand holding the ...
Newton's second law generalized this hypothesis from gravity to all forces. [112] One important characteristic of Newtonian physics is that forces can act at a distance without requiring physical contact. [note 17] For example, the Sun and the Earth pull on each other gravitationally, despite being separated by millions of kilometres.
In its original concept, gravity was a force between point masses. Following Isaac Newton, Pierre-Simon Laplace attempted to model gravity as some kind of radiation field or fluid, [citation needed] and since the 19th century, explanations for gravity in classical mechanics have usually been taught in terms of a field model, rather than a point ...
Newton updated the second edition of Optics (1717) with another mechanical-ether theory of gravity. Unlike his first explanation (1675 – see Streams), he proposed a stationary aether which gets thinner and thinner nearby the celestial bodies. On the analogy of the lift, a force arises, which pushes all bodies to the central mass. He minimized ...
A common misconception occurs between centre of mass and centre of gravity.They are defined in similar ways but are not exactly the same quantity. Centre of mass is the mathematical description of placing all the mass in the region considered to one position, centre of gravity is a real physical quantity, the point of a body where the gravitational force acts.