Concept
Inertia
Overview
Inertia is the natural tendency of objects in motion to stay in motion and objects at rest to stay at rest, unless a force causes its velocity to change. It is one of the fundamental principles in classical physics, and is described by Isaac Newton in his first law of motion (also known as The Principle of Inertia). It is one of the primary manifestations of mass, one of the core quantitative properties of physical systems. Newton writes:
LAW I. Every object perseveres in its state of rest, or of uniform motion in a right line, except insofar as it is compelled to change that state by forces impressed thereon.
In his 1687 work Philosophiæ Naturalis Principia Mathematica, Newton defined inertia as a property:
DEFINITION III. The vis insita, or innate force of matter, is a power of resisting by which every body, as much as in it lies, endeavours to persevere in its present state, whether it be of rest or of moving uniformly forward in a right line.
Overview adapted from Wikipedia (CC BY-SA 4.0; see the article history for authors).
In the original texts
Passages from public-domain books where Inertia is discussed.
_The Principle of Inertia_ In the new dynamics, the principle of inertia is still true, that is to say that an _isolated_ electron will have a straight and uniform motion. At least this is generally assumed; however, Lindemann has made objections to this view; I do not wish to take part in this discussion, which I can not here expound because of its too difficult character.
Henri Poincaré, The Foundations of Science
names the idea; states what it is; opens on it
For each of us has the immediate knowledge (be it thought true or fallacious) of his free spontaneity, without the notion of inertia having anything to do with this knowledge. But, if we wish to define the inertia of matter, we must say that it cannot move or stop of its own accord, that every body perseveres in the state of rest or motion so long as it is not acted upon by any force: and in both cases we are…
Henri Bergson, Time and Free Will
states what it is; names the idea
To take one instance out of many: he compares inertia to the original limitation of creatures, and says that as inertia is the obstacle to the complete mobility of bodies, so privation, or lack, constitutes the essence of the imperfection, or evil, of creatures. His metaphor is of boats in the current of a river, where the heavier one goes more slowly, owing to inertia.
John Dewey, Leibniz's New Essays Concerning the Human Understanding
names the idea; states what it is
Cunning must be met by cunning; proud pretension by inertia, by a low tone of patriotic sorrow; low, but incurable, unalterable. Wise as serpents; harmless as doves: what a spectacle for France!
Thomas Carlyle, The French Revolution
a chapter is titled for it; opens on it; names the idea
Proceeding on these principles, it may be argued that the molecular mobility of a substance must depend partly on the inertia of its molecules; partly on the intensity of their mutual polarities; partly on their mutual pressures, as determined by the density of their aggregation; and (where the molecules are compound) partly on the molecular mobilities of their component molecules. Whence it is to be inferred that…
Herbert Spencer, The Principles of Biology, Volume 1
names the idea; opens on it
Related ideas
- Epicurus
- Force
- Avicenna
- General relativity
- Theory of impetus
- Western philosophy
- Isaac Newton
- Classical physics
- Johannes Kepler
- Jean Buridan
- Mass
- Warring States period
- Velocity
- Motion
- Drag (physics)
- Polymath
- René Descartes
- Renaissance
- John Philoponus
- Special relativity
- Galileo Galilei
- Aristotle
- Nicolaus Copernicus
- Joseph Needham
Place in the tradition
Part of History of philosophy in Poland.