# What is inertia?

Elena Melnichenko
February 9, 2015
13040

The word "inertia" is associated with physics, but we often use it in everyday life without reference to this science. Let's see what is inertia.

## Meaning of the word

This word came to us from the Latin language: inertia. Inertia means inaction.

Inertia is a property of the body to maintain the original state of rest or uniform motion, when no forces act on it (the cart was rolling by inertia).

The word is also used in a figurative sense: inertia means the absence of initiative, inactivity. In this connection, the expression “to do something by inertia” or “to live by inertia” is common in the people, which means to perform some actions out of habit, without making special efforts. The phrase “go with the flow” is synonymous.

There is also an adjective "inert". It, as you have already guessed, can be replaced by the word "inactive".

## Newton's inertia in law

The famous physicist Isaac Newton proclaimed the existence of inertial reference systems, that is, suchwith respect to which moving bodies maintain their speed unchanged, if other bodies do not act on them or the action of other bodies is compensated. This is the so-called Newton's first law. It is also called the law of inertia, since this phenomenon of preserving the velocity of a straight-line uniform motion (or rest) of a body is called inertia.

There are also other reference systems, but all of them, whatever - moving with acceleration or rotating - will be called non-inertial.

It cannot be said that Newton was a pioneer in this matter, since he relied on the works of G. Galileo, who first stated that if a body is not acted upon by another force, this does not mean that it is at rest. On the contrary, it is the state of uniform and rectilinear movement that seems to be natural for the body, and rest is rather a particular case of such movement, the speed of which is zero. This uniform and rectilinear motion of a free body itself is called inertial motion.

### Force of inertia

In physics, there is also such a thing as inertia. This term is widely used in mechanics.This concept applies to the d'Alembert, Euler, Newtonian forces.