Isaac Newton: Physics, Calculus, and the First Law of Motion

Isaac Newton: Life and Legacy

Isaac Newton was born in 1642, the year Galileo also died. Almost all of his creative years were spent at the University of Cambridge, England, first as a student, then as a highly distinguished teacher. He never married, and his personality continues to puzzle scholars today: reserved, sometimes cryptic, and embroiled in personal quarrels. He gave his attention not only to physics and mathematics, but also to religion and alchemy.

The only thing that everybody agrees on is his brilliant talent. Three problems intrigued scientists at the time:

• The laws of motion
• The laws of planetary orbits
• The mathematics of continuously variable quantities (a field now known as differential and integral calculus)

It can be said with justice that Newton was the first to solve these three problems.

In 1687, he surprised the world with the publication of his book Mathematical Principles of Natural Philosophy. This book also describes the theory of universal gravitation and formulates the three laws of motion.

Newton argued that all movements are in line with three main laws formulated in mathematical terms, involving concepts that first need to be defined rigorously. One concept is force, the cause of movement; another is mass, measuring the amount of matter set in motion. These two are commonly represented by the letters F and m.

Newton's First Law of Motion

The first example of movement, and probably the only one that could be described mathematically by Newton, is falling objects. However, there are other movements, especially panning, in which gravity does not play a major role. Newton's laws were also applied to them.

And observing several bodies in horizontal motion, one could conclude:

"Straight-line motion at constant speed requires no force."

Adding this movement to any other brings no new force into play; everything remains the same. In the cabin of an airplane moving in a straight line at a constant speed of 600 mph, nothing changes: the coffee pours the same way, and a spoon continues falling straight down.

Thus, it was concluded that a body will maintain its state of rest or uniform rectilinear motion where the net force is zero.