Gravity

Gravity

The gravitational force at the surface of the planet is the force that binds all bodies to earth, this force is one of the four forces recognized by physicists, and this kind of force is known as "gravity" it attracts every celestial object to earth, and though it is the most important of the forces essential for our lives, it is the least comprehended of them all Throughout ages scientists have tried to solve the mystery of gravity, and one of the first discoveries concerning gravity was made by Aristotle who concluded from his experiments that the downward movement of any body is that has weight had a proportional relationship between its quickness in motion and its size. However this theory was accepted for centuries, but after a series of experiments made by Galileo, Aristotle's theory was proved to be incorrect, as Galileo said after a series of experimenting at the Pisa tower that bodies of different sizes fall with the same speed. Later on, the idea that the force is needed so as to change the motion of the body was discovered. After that a great scientist was to improve all the previously accepted theories, this scientist was Newton who was to make decisive advances in understanding gravity. In his first law Newton said that a body in state of rest or uniform motion in a straight line will keep on moving unless acted upon by a force, while in his second Newton expressed his first law in a more quantitative way as he said that force acting on a body is the rate of change of it's momentum which can be put in a rule as F= ma Where (F) is the force acting on the body while (a) and (m) are the acceleration and inertial mass of the body respectively. Newton also made the law of gravitation in which he expressed the gravitational force of attraction between any two bodies acting along the line joining them as Where (m) is the mass of the two bodies and (r) is the distance between them, while (G) is the proportionality constant known as the constant of gravitation, afterwards Newton made his very important assumption in which he showed that the inertial mass of a body is identical to its gravitational mass which implied that the gravitational force exerted on or by an object is directly proportional to its inertia.