What are Newton’s Laws of Motion?

What are Newton’s Laws of Motion?

“Principia” offers an exact description of bodies in motion, with three basic laws of motion:

1) A stationary body will stay stationary unless an external force is applied to it.

2) Force is equal to mass times acceleration, and a change in motion (i.e., change in speed) is proportional to the force applied.

3) For every action, there is an equal and opposite reaction.

What is Newton’s Theory of Gravity?

Newton’s three basic laws of motion helped him arrive at his theory of gravity. Newton’s law of universal gravitation states that two objects attract each other with a force of gravitational attraction that’s proportional to their masses and inversely proportional to the square of the distance between their centers.

These laws helped explain not only elliptical planetary orbits but nearly every other motion in the universe: how the planets are kept in orbit by the pull of the sun’s gravity; how the moon revolves around Earth and the moons of Jupiter revolve around it; and how comets revolve in elliptical orbits around the sun. They also allowed him to calculate the mass of each planet and how the gravitational pull of the sun and the moon create the Earth’s tides. According to Newton, gravity kept the universe balanced and made it work.

What is Newton’s Legacy?

Isaac Newton's fame grew even more after his death, as many of his contemporaries proclaimed him the greatest genius who ever lived. Maybe that is a slight exaggeration, but his discoveries had a large impact on the Western world, leading to comparisons to the likes of Plato, Aristotle and Galileo.

Although his discoveries were among many made during the Scientific Revolution, Isaac Newton's universal principles of gravity found no parallels in science at the time. Of course, Newton was proven wrong on some of his key assumptions. In the 20th century, Albert Einstein would overturn Newton's concept of the universe, stating that space, distance and motion were not absolute but relative, and that the universe was more fantastic than Newton had ever thought.

Newton might not have been surprised: In his later life he said, "I do not know what I may appear to the world; but to myself I seem to have been only like a boy playing on the seashore, and finding a smoother stone or prettier shell than ordinary, while the great ocean of truth lay all undiscovered before me."

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