Sir Isaac Newton's


Three Laws of Motion 

Physics 212 Spring 2003

by Amanda J. Nebert


We have all heard the story of the apple falling on Newton's head while he was sitting against the tree, thus

giving him the sudden idea for the Universal Law of Gravity. This, as I am sure most of us know, is not really

what happened. A more accurate version would probably be, Newton observed an apple falling from a tree

and started contemplating the physics of the apple's fall. The acceleration experienced by the apple, which

started at zero when hanging in the tree, then increased as the apple fell. This as Newton reasoned from his

second law of motion, means there must be a force acting upon the apple in order to cause the acceleration,

this force we will call gravity. Thus giving us the acceleration due to this force as "acceleration due to gravity,"

a term most of us have probably heard. This idea is known as Newton's Universal Law of Gravity. This idea

is basically Newton's second law of motion which we will look at more in depth. We will also look at Newton's

other two laws of motion.



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