Sir Isaac Newton Also known as the father of Physics , this was the man who created a new subject (Physics) out of the basic sciences. He was very engrossed in his studies. He used to study for 24 hours continuously. He had high observation powers which helped him discover few of the most importan concepts in Science (such as gravity).Newton discovered how the universe is held together through his theory of gravitation. He discovered the secrets of light and colour. He invented a branch of mathematics, calculus, also invented independently by Gottfried Leibniz, a German mathematician . Newton made these three discoveries within 18 months from 1665 to 1667.

The theories of motion and gravitation.

Newton said the concept of a universal force came to him while he was alone in the country. He had been forced to flee there because of the outbreak of bubonic plague in the city of Cambridge. During this time, Newton suddenly realized that one and the same force pulls an object to earth and keeps the moon in its orbit. He found that the force of universal gravitation makes every pair of bodies in the universe attract each other. The force depends on (1) the amount of matter in the bodies being attracted and (2) the distance between the bodies. The force by which the earth attracts or pulls a large rock is greater than the pull on a small pebble because the rock contains more matter. The earth's pull is called the weight of the body. With this theory, Newton explained why a rock weighs more than a pebble.

He also proved that many types of motion are due to one kind of force. He showed that the gravitational force of the sun keeps the planets in their orbits, just as the gravitational force of the earth attracts the moon. The falling of objects on earth seems different from the motion of the moon because the objects fall straight down to the earth, while the moon moves approximately in a circle around the earth. Newton showed that the moon falls just like an object on earth. If the moon did not fall constantly toward the earth, it would move in a straight line and fly off at a tangent to its orbit. Newton calculated how much the moon falls in each second and found the distance is 1/3600 of the distance an object on earth falls in a second. The moon is 60 times as far from the earth's centre as such an object. Consequently, the force of the earth on an object 60 times as far away as another object is 1/3600.