# 11-1 - Perhaps all the way to the moon By careful observation and measurement Newton discovered that the gravitational attraction between two

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Tyler Liebnau According to legend, Isaac Newton suddenly thought of the Universal Law of Gravitation when an apple fell on his head. The story probably contains the seeds of what actually happened. Newton had already framed his three laws of motion. The first law stated that a force must act on an object to accelerate it (change its velocity). An apple on a tree has a velocity of zero (0), so when it falls, its velocity increases. Newton reasoned that a force must have acted on it. We expect this force to act on the apple from a 10-foot tree or from the top of a 100-foot tower. What if this force extended on and on?
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Unformatted text preview: Perhaps all the way to the moon! By careful observation and measurement, Newton discovered that the gravitational attraction between two objects depends on their mass and their distance. The larger the objects, the greater the attraction between them. The greater the distance, the lesser the attraction. Newton showed that the Earth and all other objects in the universe exert pulling forces on each other —gravitational forces. Ocean tides show the moon’s gravitational force on the Earth. The moon remaining in orbit shows the Earth’s gravitational force on it....
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## This note was uploaded on 10/04/2011 for the course ECON 101 taught by Professor Vladimir during the Fall '11 term at Central Mich..

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