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350
Aristotle
His theory was to all bodies move towards their natural place. Aristotle lso concluded that the heavier an object was, the faster it would tend to fall compared to light weight objects. Link:http://www.flickr.com/photos/inkyfingerz/3659782848/ -
352
Ptolemy (352)
His theory was on Aristotle's theory but believed everything falled back onto Earth and not its "natural place" since Earth is the center. To prove this, he experimented with circles stating every planet,sun and moon moved around in their own epicycles oribiting Earth. Link:http://www.kidsnewsroom.org/elmer/infocentral/space/html/exploration/people/ptolemy.html#theory -
Newton
His theory took some idea off of Ptolemy's theory but addded more ifo about the moon. The law of gravity came upon him as he was sitting under a tree in a garden when an apple fell on top of his head. It made him think that the same force that was upon the apple is the same force that keeps the moon in orbit. This is why the moon stays in orbit and does not fall. The moon has no gravity nor acceleration to fall unto earth. Link:http://www.kidsnewsroom.org/elmer/infocentral/space/html/ex -
Cavendish
Cavendish wanted to find out the density of the Earth; In other words, "weigh the world". He conducted an experiment by measuring the force on a small ball caused by a large ball versus the force on the small ball caused by the Earth. Link: http://www.juliantrubin.com/bigten/cavendishg.html -
Einstein
Einstein's theory was that gravity is not a force but a "fourth dimension" Link:http://science.howstuffworks.com/environmental/earth/geophysics/question2322.htm