The Apple Incident
Everybody knows about the famous 'apple incident' - when Isaac Newton was sitting under an apple tree when one fell on his head and he thought of the theory of gravity, like most legends this story has some artistic licence.
A more accurate story would be Newton watching and apple fall from a tree and ask himself: what made the apple fall? Due to Newtons 2nd law we know that there must be a unbalanced force applied to something in order for it to accelerate - which the apple was doing since its velocity went from nothing to accelerating towards the ground (falling). So there must be a force being applied to the apple that causes it to fall towards the ground and can reach up to the highest apple tree - Newton called this force Gravity. This means that the reason the apple fell was acceleration due to gravity. This discovery lead Newton on a path that has changed everything that we knew about the earth back then. He thought that if Gravity could reach up to the highest apple tree , what if it could reach further? Using the knowledge that he gained from Galeios research he discovered that the moon rotated the earth due to gravitational force. After Newton conducted more experiments and came up with theories, he came up with the law of Universal Gravitation: Every object in the universe attracts every other object with a force directed along the line of centers for the two objects that is proportional to the product of their masses and inversely proportional to the square of the separation between the two objects. |