Al-Khāzini concept of gravity

Abu al-Fath Abd al-Rahman Mansour al-Khāzini or al-Khāzini defined gravity as a universal force directed towards the center of the Earth.

Two pages from Book of the Balance of Wisdom

Al- Khāzini originally a Greek slave who flourished in Merv at the beginning of the 6th/7th century and who continued the study of mechanics and hydrostatics in the tradition of al-Biruni and the earlier scientists.

In his books The Book of the Balance of Wisdom completed in 1121 in Merv al-Khāzini he doevd his work in eight treatises:
*Theories of centers of gravity according to various Greek and Arabic scholars
*Further discussion on centers of gravity; mechanism of steelyard
*Comparative densities of various metal and precious stones, according to al-Biruni
*Balances designed by various Greek and Arabic scholars
*The water balance of Umar Khayyam – its design, testing and use
*’The balance of Wisdom; determination of the constituents of alloys
*Weights of coinage
*The steelyard clepsydra

The Book of the Balance of Wisdom is perhaps the most essential Muslim work on mechanics and hydrostatics and especially the study of centers of gravity.
Al-Khazini concept of gravity

Galileo Galilei and Law of Free Fall Object

The Italian Galileo Galilei (1564-1642) originated the present day ideas concerning falling objects.  He was one of the first scientists to assert that all objects fall with the same acceleration.

Galileo a 24 year old mathematics professor at the University of Pisa, Italy often sat in local cathedral when some nagging problem weighed on his mind.

Lamps gently swung on long chains to illuminate the cathedral. One day in the summer of 1598, Galileo realized that those lamps always at the same speed.

He decided to time them. He used pulse in his neck to measure the period of each swing of one of the lamps. Then he times a larger lamp and found that it swung at the same rate. He immediately set up an experiment that revealed the pendulum principle.

Over many days he timed the lamps and found that they always took exactly the same amount of time to travel through one compete arc.

On his essay On Motion, Galileo gave an argument in support of the idea that objects of different weights fall at the same rate – that is, that their speed of falling does not depend on their weight.

He stated that heavy objects would fall faster than lighter objects.
Galileo Galilei and Law of Free Fall Object 

The Universal Law of Gravitation

The universal law of gravitation was discovered by Newton in the seventeenth century. Before Newton’s discovery, no one knew of the existence of such law.

The year was 1665; the month was August. Newton, then a 23 year old Cambridge University student retired to the solitude of his family’s farm. The university was closed for two years because of the Greta Plaque.

There is a story that Isaac Newton was inspired by the fall of an apple, to consider whether gravity was responsible for the motion of the moon as well. He was wondering what force could hold the moon in its path when the fall of an apple made him think that it might be the same of gravitational force.

With the idea of gravity fixed in his mind, Newton began the task of determining the mathematics involved in universal gravitation.

Newton himself never wrote about that day in the orchard, but he did reminisce about it to friends some 50 years later.

Newton’s realization that gravity is universal had important implications. Newton recognized that the laws of motion must also be universal in character.

Newton’s law of gravitation was the first theory to accurately describe the motion of objects on Earth as well as the planetary motion that astronomers had long observed. 

According to Newton’s universal law of gravitation ‘every particle in the universe attracts every other particle in the universe with a force that is directly proportional to the product of the masses of those particles and inversely proportional the square do the distance between those particles.

Newton’s law led to many new discoveries, the most important of which was the discovery of the planet Neptune in 1864.
The Universal Law of Gravitation