In physics, capital G represents the universal gravitational constant, a fundamental constant that appears in Newton's law of universal gravitation and Einstein's theory of general relativity.
The universal gravitational constant, also known as the Newtonian constant of gravitation or the Cavendish gravitational constant, is typically denoted by the symbol G. It quantifies the strength of the gravitational force between two objects. Its approximate value is:
- G = 6.674 × 10-11 N⋅m2/kg2 (Newton meters squared per kilogram squared)
Significance of G
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Newton's Law of Universal Gravitation: G is crucial in the equation F = G (m1m2)/r2, where F is the gravitational force between two masses (m1 and m2) separated by a distance r.
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General Relativity: G also plays a significant role in Einstein's field equations, which describe the relationship between the geometry of spacetime and the distribution of matter and energy.
Determining the Value of G
Unlike many other fundamental constants, G is notoriously difficult to measure with high precision. Henry Cavendish first experimentally determined its value in 1798 using a torsion balance. Modern experiments continue to refine its value, but it remains the least precisely known of the fundamental constants.
In Simple Terms
Imagine two bowling balls placed near each other. The gravitational constant G tells you how strongly they attract each other due to gravity. Although this force is incredibly weak for objects of everyday size, it becomes significant when dealing with massive objects like planets and stars.
