Sir Isaac Newton developed 3 laws which describe motion both on Earth and in the heavens.

Up until that time, physicists could describe motion, as we have learned to do. But it took a young Englishman named Isaac Newton to explain it.

Earlier sections talked about the role of laws in physical science. Using the language of mathematics, physicists can describe what is happening. They then formulate laws to explain how things happen. Finally, those laws can be used to predict what will happen.

Think about all of the descriptions of motion discussed so far. Let's say you look out the window and see your physics teacher roller-blading by. Her speed, direction of motion, displacement, and acceleration could be described with a sentence such as "Ms. Nye is skating eastward at 2 m/s." You could even create a position-time or velocity-time graph of Ms. Nye's motion.

But would any description, verbal or graphical, predict Ms. Nye's future motion? No. Kinematics (descriptions of motion without regard to its cause) cannot predict anything. But many people would argue that, calculating Ms. Nye's current position and acceleration, it is possible to predict, for example, that she will arrive at school in 30 minutes.

Maybe so, but this prediction wouldn't come from a description of her motion. Predicting motion requires explanations of the causes of changes in motion, a field called DYNAMICS. Newton's laws of motion discussed in this section form the foundation of dynamics.

Aristotle's model of the universe took into account the charted movements of the heavenly bodies, but was complicated by the assumption that Earth lay at the center of the universe.

For instance, Newton's first law states that an object in motion will remain in motion unless acted upon by an unbalanced force. Today, this may seem an obvious statement, but it was so revolutionary at the time that the formulation of Newton's laws stands as the single most remarkable achievement in science.

Prior to Newton's explanation of motion, there were other explanations, to be sure. The movement of the Sun around the Earth (yes, that's really what people thought) was explained by divine action.

In their explanations of motion, Aristotle, Ptolemy, and the other ancients assumed an immovable Earth. This model was supported by everyday observation. Like you, Aristotle could roll a ball and observe that it eventually stopped moving. Unlike you, however, he knew nothing about the force of friction. This led him to conclude that the ball, like the Earth, did not move because there was no force acting to keep it in motion.

The obvious problem with these and all other explanations of motion prior to Newton's was that they did not accurately predict the behavior of moving planets, balls, or physics teachers. Thus, the stage was set in 1661 for the young English mathematician to literally move heaven and Earth.