The three laws of motion: firstly, that a body will only moved when acted on by an outside force (see: external force); two, that greater the force, the greater the change in motion (aka acceleration); third, that for every action (force) there is an equal and opposite reaction (force), which implies that forces are always found in pairs (see also: conjugate variables). [3] |
See main: First law of motionGreek philosopher-scientist Aristotle (384-322BC) was one of the first to grapple with the outlines of the first law; discussions of which resulting from his investigations into the nature abhors a vacuum query, which he was an advocator of. Aristotle’s proto-version version of the first law was: [4]
“Nobody can give a reason why a body that has been put into motion in empty space should stop on its own account. Why should it stop in one place rather than in another? Thus it will remain at rest, or it will of necessity keep moving ad infinitum unless it is hindered from doing so.”
“Bodies will have a rapid motion through a vacuum where there is nothing to obstruct or repel them, until they are in contact.”
The 1687 original rendition of the laws of motion by Isaac Newton, according to the English translation by Andrew Motte (1850). [7] |
“Nothing whatever can be moved by itself, but its motion is effected through another. There is no other force.”
“All movement tends to maintenance, or rather that all moved bodies continue to move along as the impression of the force of their motors (original impulse) remains in them.”
“Every body perseveres in its state of being at rest or of moving uniformly straight forward, except insofar as it is compelled to change its state by forces impressed.”
See main: Second law of motionThe second law of motion, according to Newton (1687), states that:
“A change in motion is proportional to the motive force impressed and takes place along the straight line in which that force is impressed.”
See main: Third law of motionIn circa 340BC, Greek philosopher Plato stated the following:
“The excessive increase of anything causes a reaction in the opposite direction.”
“See how the wings, striking the air, sustain the heavy eagle in the thin air on high. As much force is exerted by the object against the air as the air against the object.”
“To any action there is always an opposite and equal reaction; in other words, the actions of two bodies upon each other are always equal and always opposite in direction.”
“Descartes discovered coordinate geometry and the first two laws of motion, while Galileo discovered the acceleration due to gravity and the two moons of Jupiter.”— Thomas Conlon (2011), Thinking About Nothing (pg. 319)