Saturday, September 11, 2010

GRAVITATIONAL FORCE


DID YOU KNOW THAT: Objects fall to the ground as a result of the attracting force between earth and the object? Newton was the first person to establish this fact. It has been known since earliest times that falling bodies undergo accelerated motion. The Greek philosopher, Aristotle (384 – 322 B.C.), maintained that heavier objects fall faster than lighter objects. He had no experimental proof for this incorrect statement. He also stated that objects fell to the ground and that clouds rose up to find their “natural position”. These doctrines were accepted for many centuries until the invention of the cannon stimulated further research about the motion of falling bodies and projectiles. Galileo (17th century) was the first person to investigate Aristotle’s statement by means of experiment. He climbs up the leaning tower of Pisa with a piece of great mass and light objects like fluff, chicken feather et cetera. He drops them simultaneously from the same height above the building. He realized that air resistance influenced the falling of light object, feather and fluff, and water droplets in clouds to a large extent.
Although Sir Isaac Newton’s discovery of the Law of Universal Gravitation represents one of the greatest scientific achievements of all times, he was led to this discovery partly by the work of early astronomers and partly by his own remarkable insight into the laws of nature. It is said that Newton began speculating about gravitational forces when he noticed an apple fall to the ground. He knew that the apple fell because of the earth’s gravitational force of attraction, but then it occurred to him that the apple might attract the earth or that one apple might attract another, he extended this concept and considered that there might be gravitational attraction between all heavenly bodies.
Since objects accelerate towards the earth, it follows that the earth exerts an attracting force on them. According to Newton’s third law of motion the objects must, however, also exert a force of the same magnitude on the earth, but in opposite direction. Newton then deduced that any two objects in the universe exert a force of attraction on one another. Newton called this mutual force of attraction gravitational force (or the force of gravity).
This blog is about Newton's Law of Universal Gravitation. Learners are exposed to the nature and effects of Gravitational Force as it acts on heavenly bodes. The Web site will cover the task, the process, assessment and contents of the lesson plan for the 12th grade in Physical Sciences.

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