Everyone going to school and listening carefully to what the teacher says should already know about Newton’s laws of universal gravitation. However, if it was quite some time ago, this article will refresh knowledge quickly.

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**Sir Isaac Newton prior to Newton’s Laws of Universal Gravitation**

Isaac Newton was born at Woolsthorpe, Lincolnshire, on December 25, 1642. His widowed mother remarried when he was three years old, leaving him in the care of his grandmother. When she became a widow for the second time, she opted to send him to Grantham Grammar School. In 1661, he enrolled at Trinity College, Cambridge University, where he earned his teaching diploma.

He dedicated himself to studying and researching the most recent advances in mathematics and natural philosophy during that period. He quickly discovered vital findings that would be extremely useful to him throughout his professional career. He also addressed light and optics problems, developed laws of motion, and inferred what is now known as Newton’s laws of universal gravitation from them.

Newton’s laws of universal gravitation assert that the force of attraction experienced by two masses is directly proportional to the product of their groups and inversely proportional to the square of the distance between them (law of the inverse of the court of the space). The law includes a proportionality constant (G) known as the universal gravitation constant, the value of which has been determined by precise experiments to be: G = 6.67384 * 10-11 N*m²/kg².

**What is Gravitation?**

Gravitation is the force of mutual attraction that bodies experience due to their mass.

According to Newton’s Laws of Universal Gravitation, every particle of matter in the cosmos, believe it or not, exerts a gravitational attraction on every other particle. The phrases “gravitation” and “gravity” are sometimes used interchangeably to describe the attraction between all things with energy or mass.

In the 17th century, the English mathematician and scientist Isaac Newton confirmed the existence of this force. Furthermore, this bright scientist created the so-called fluxions calculus for its formulation (known today as integral calculus).

**Gravitation between Galaxies and Planets**

The acceleration with which a test body (of unit radius and mass) falls inside this field is established to estimate the strength of the gravitational field associated with a body of a certain radius and mass. The acceleration of gravity may be calculated using Newton’s second law, the force of gravity, and a specified mass.

This acceleration has different values depending on the body on which it is measured; thus, for the Earth, a value of 9.8 m/s² (equivalent to 9.8 N/kg) is considered, while the value obtained for the surface of the Moon is only 1.6 m/s², that is, about six times less than that corresponding to our planet. In one of the solar system’s giant planets, Jupiter, this value would be about 24.9 m/s².

Due to the existence of universal gravitation, the centrifugal force equals the centripetal force in an isolated system formed by two bodies, one of which revolves around the other, the first having a much smaller mass than the second and describing a stable and circular orbit around the body occupying the center.

From such considerations, one of Kepler’s laws (the third) may be deduced; which connects the radius of the orbit that a body describes around another central body to the time it takes to sweep the area that such circle encloses, and which specifies that time is proportional to 3/2 of the radius.

This conclusion has general application and is also valid for elliptical orbits. The circular orbit is a unique instance where the semi-major and minor axes are equal.

**Famous Apples of Sir Isaac Newton**

Legend has it that a young Isaac Newton was hit on the head by an apple falling from a tree. In reality, there is no evidence that the fruit fell on his head. Instead, it was his observation of why apples always fall straight to the ground. This observation of a falling apple inspired him to develop his universal gravitation law.

https://www.history.com/news/did-an-apple-really-fall-on-isaac-newtons-head

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