Isaac Newton Isaac Newton Isaac Newton is regarded by most as the greatest figure in the history of science. Among his many distinctions, he is credited with… …the universal theory of gravity… …the invention of the reflecting telescope.. …the invention of calculus… …the discovery of the spectrum of colors… …and the first theories of the speed of sound and the origins of stars.

Isaac Newton three laws of motion However, he is most famous for developing the three laws of motion. Philosophiae Naturalis Principia Mathematica On July 5, 1687, he published Philosophiae Naturalis Principia Mathematica. In this groundbreaking book, he laid out the laws that all objects must obey when dealing with gravity and motion.

Newton’s First Law Newton’s first law states: An object at rest stays at rest and an object in motion stays in motion until acted upon by another force. Basically, objects keep on doing what they’re doing unless some kind of force interrupts. Need proof? This is why a seat belt saves your life in a car crash. The car and you are moving. The tree stopped the car. The seatbelt makes you a part of the car. What happens if there’s no force (seatbelt) to stop you? Inertia Also known as the Law of Inertia. Inertia is the reluctance of an object to change its state of motion. Basically, “inert” means stubborn and unchanging.

Newton’s Second Law Newton’s second law states: The acceleration of an object depends on the mass of the object and the amount of force applied to the object. Basically, the larger an object is, it will take more force to move it and the slower it will accelerate. Need proof? Pushing your friend in a toy tractor is easy. Pushing your friend’s pet elephant? Not so easy, is it? Why?

Newton’s Third Law Newton’s third law states: For every action, there is an equal and opposite reaction. Basically, forces come in pairs. Wherever there is one force there is always another. The result always comes down to mass. Need proof? When you dribble a basketball, the ball hits the Earth AND the Earth hits the ball. There are two forces working. Because the Earth has a MUCH larger mass than the ball, it moves much less slowly when it is it.

Newton’s Second Law The acceleration of an object depends on the mass of the object and the amount of force applied to the object. This can be summed up in an easy equation. Force = Mass X Acceleration Or, if you want to shorten it… F=MA Let’s check out that second one again…

Newton’s Second Law When you smack a tennis ball as hard as you can with a tennis racket, the ball flies far and fast. Try using that same racket with the same force but with a baseball instead. What’s going to happen? The ball doesn’t go as far or as fast and you’re lucky if your racket doesn’t end up looking like this guy’s. Why? As the mass of the ball goes up, your force better go up, too, or the ball is not going to accelerate as fast.

Newton’s Second Law The larger the mass, the slower the motion. So let’s sum up that second law. The smaller the mass, the faster the motion. The larger the force, the faster the motion. The smaller the force, the slower the motion. Smaller equals quicker. The smaller the force, the slower the motion and vice versa.