# What is Inertia in Physics | Definition, Types – Laws of Motion

Inertia Definition Physics :
The property of an object by virtue of which it cannot change its state of rest or of uniform motion along a straight line on its own, is called inertia. Greater the mass of a body greater will be its inertia and vice-versa.

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## What is Inertia in Physics | Definition, Types – Laws of Motion

Inertia is of three types:

(i) Inertia of rest Definition:
It is defined as the tendency of a body to remain in its position of rest, i.e., A body at rest remains at rest and can not start moving on its own.

(ii) Inertia of motion Definition:
It is defined as the tendency of a body to remain in its state of uniform motion along a straight line, i.e., A body in uniform motion can neither gets accelerated nor get retarded on its own, also it cannot stop on its own.

(iii) Inertia of direction Definition:
It is defined as inability of a body to change by itself its direction of motion.
Types of Motion in Physics
1. One Dimensional Motion Definition :
If only one out of three coordinates specifying the position of the object changes with respect to time, then the motion is called one dimensional motion or rectilinear motion.

For instance, motion of a block in a straight line, motion of a train along a straight track, a man walking on a level and narrow road and object falling under gravity etc.

2. Two Dimensional Motion Definition:
If only two out of three coordinates specifying the position of the object change with respect to time, then the motion is called two dimensional motion.

A circular motion is an instance of two dimensional motion.

3. Three Dimensional Motion Definition:
If all the three coordinates specifying the position of the object change with respect to time, then the motion is called three dimensional motion. A few instances of three dimension at motion are flying bird, a flying kite, the random motion of gas molecule etc.

Laws of Motion:
There are various laws in Physics that define the motion of the object. When an object is in motion whether it is linear or circular there is some force which is always imposed on it.