## What is Gravity

It is a fundamental force and a natural phenomenon by which all things with mass or energy are brought toward one another. Gravity is also known as gravitation. It has an infinite range, although its effects can become increasingly weaker as objects get further away. This is a free-falling force where all the objects are proportional to each other. Which states that gravity is responsible for many large-scale structures in the universe. It is the weakest of all the other four forces. This force has universal attraction acting between all matter. Gravity has a downward force that is proportional to its mass. It is measured by the acceleration that it gives to a free-falling object.

## How gravity works.

It is the weakest of the four fundamental interactions of physics. The invisible force pulls the object towards each other. However, for most applications, gravity is well approximated by Newton’s law of universal gravitation, which describes gravity as a force causing any two bodies to be attracted toward each other, with a magnitude proportional to the product of their masses and inversely proportional to the square of the distance between them.

## Ancient History

In ancient Greek philosopher Archimedes discovered the center of of a triangle. He also postulated that if two equal weights did not have the same center of gravity.

In ancient India, Aryabhata first identified the force to explain why objects are not thrown outward as the earth rotates. Brahmagupta described gravity as an attractive force and used the term “Gurutvaakarshan” for gravity.

## Scientific advancements

Modern work on gravitational theory began with the work of Galileo Galilei which was in the 16th century. His work continued to the early 17th century. One of his famous experiment was dropping balls from the Tower of Pisa. Which later became balls rolling down inclines.

Galileo showed that gravitational acceleration is dame for all the objects irrespective of weight. Which was major departure from Aristotle’s belief that heavier objects have higher gravitational acceleration.

Galileo presented that air resistance is the reason that objects with less mass fall more slowly in an atmosphere. This work set up a stage for the formulation of Newton’s theory of gravity.

## Theory of Gravitation

In 1687 Newton’s theory about masses, planets, and orbits enjoyed its greatest success. As it predicted the existence of Neptune based on motions of other planets. Which led to the discovery of Neptune by Johann Gottfried Galle.

Later it was discovered that there was a flaw in Newton’s theory. The discrepancy in Mercury’s orbit pointed out flaws from that theory. By the 19th century, it was known that there were slight perturbations that could not be accounted for entirely under Newton’s theory. This issue was later resolved by 1915 by Albert Einstein’s new theory of general relativity. Which accounted

The equivalence principle, it expresses the idea that all objects fall in the same way. The effects of gravity are indistinguishable from certain aspects of acceleration and deceleration.

The simplest way to test the weak equivalence is to drop to objects of different masses or compositions in a vacuum and see whether they hit the ground at the same time.

Such experiments demonstrate that all objects fall at the same rate when other forces (such as air resistance and electromagnetic effects) are negligible.

## General Relativity

The effects of gravitation are ascribed to spacetime curvature instead of a force. It equates free fall with inertial motion and describes free- falling inertial objects as being accelerated relative to non-inertial observers on the ground.

But in Newtonian physics, however, no such acceleration can occur unless at least one of the objects is being operated on by a force. Later Einstein proposed that spacetime is curved by matter. These free-falling objects are moving along locally straight paths in curved spacetime. These straight paths are called Geodesics. Like Newton’s first law of motion, Einstein’s theory states that if a force is applied to an object, it would deviate from a geodesic.

We are no longer following geodesics while standing because the mechanical resistance of the Earth exerts an upward force on us. We are non-inertial on the ground result. This leads to explaining why moving along the geodesics in spacetime is considered inertial.

## Earth’s Gravity

Every planetary body (including the Earth) is surrounded by its own gravitational field. Which can be conceptualized with Newtonian physics as exerting an attractive force on all objects. Assume a planet that is a spherical and symmetrical planet. This field at any given point above the surface is proportional to the planetary body’s mass and inversely proportional to the square of the distance from the center of the body.

The strength of the gravitational field is numerically equal to the acceleration of objects under its influence. The rate of acceleration of falling objects near the Earth’s surface varies very slightly depending on the circumstances.

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