The pages of his monumental endeavor forever sealed his place on the pages of history. It is said that one day Newton was hit by an apple that fell while he was under an apple tree. Newton began to wonder why the apple fell down and not up. Although Galileo was the first to experiment with gravity by throwing rocks off the leaning tower of Pisa, Newton was the first to write these laws down and publish them. At the ripe age of 23 Newton wrote down the his three laws of motion that govern the universe.
Every object maintains a constant velocity unless acted upon by an unbalanced force.
Newton claimed that the larger the mass of the object, the greater the force needed to change its velocity. Inertia is simply an object's resistance to change velocity. An object keeps traveling at one speed and continues to do so until an outside force acts on it. Examples of this can include a car accident. Newton claims that objects have inertia no matter where they are.