Gravitational constant

NewtonsLawOfUniversalGravitation

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Cavendish Torsion Balance Diagram

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Gravitational constant historical

Gravitational Constant (symbol: G) is a physical constant that plays a crucial role in the law of universal gravitation, which was first formulated by Isaac Newton. This constant is a measure of the strength of gravity between two objects. The value of the Gravitational Constant is approximately 6.674 × 10^−11 N⋅m²/kg².

Overview

The concept of the Gravitational Constant is foundational in physics, particularly in the field of classical mechanics. It enables the calculation of the gravitational force between two masses. According to Newton's law of universal gravitation, the force (F) between two masses (m1 and m2) separated by a distance (r) is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers. The Gravitational Constant, G, is the proportionality constant in this equation:

\[F = G \frac{m_1 m_2}{r^2}\]

History

The Gravitational Constant was first introduced by Isaac Newton in 1687 in his seminal work, Philosophiæ Naturalis Principia Mathematica. However, the actual value of G was not measured until 1798 by Henry Cavendish using a torsion balance experiment. This experiment allowed for the calculation of the Earth's density and indirectly measured the Gravitational Constant.

Measurement

Measuring the Gravitational Constant has proven to be exceptionally challenging due to the weakness of the gravitational force compared to other fundamental forces. Various experiments over the years have yielded slightly differing values, leading to ongoing research to refine its measurement. The current accepted value, as recommended by the Committee on Data for Science and Technology (CODATA), is subject to periodic review as measurement techniques improve.

Significance

The Gravitational Constant is significant not only in the calculation of gravitational forces but also in understanding and predicting the orbits of planets, moons, and artificial satellites around larger bodies. It is also crucial in the study of astrophysics, cosmology, and black holes, as it helps in understanding the structure and evolution of the universe.

Challenges

One of the major challenges in the field of physics is the precise measurement of the Gravitational Constant. Its small value and the weakness of the gravitational force make it susceptible to experimental errors. Additionally, reconciling the gravitational force with quantum mechanics in a theory of quantum gravity remains an unresolved issue in modern physics.

See Also

• Law of universal gravitation
• Classical mechanics
• Astrophysics
• Cosmology