Inertial and Non-Inertial Frame of Reference - JEE Important Topic

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In Physics and Astronomy, a reference frame refers to an abstract coordinate system whose direction, origin, and scale are specified by a set of geometric reference points. The frame of reference has physical reference points that uniquely fix the coordinate system and standardise measurements within that frame of reference. In this article, we will have a deep insight into the concept of reference frames, the types of reference frames, and the difference between inertial and non-reference frames of reference.

Types of Frame of Reference

According to Newton's law, if an object has a net force of zero, its acceleration will also be zero. In this case, the body may be stationary or evenly moving with a constant velocity vector. A different frame of reference was observed. A reference frame in which the first law of motion is valid and the coordinate system that can be directly applied is known as the inertial system. Moreover, reference frames to which Newton's first reference law does not apply directly are non-inertial reference frames.

Thus, the frame of reference is widely differentiated into two types:

Example of Frame of Reference

Before we start with other frames of reference, we will first understand the concept of the frame of reference with a few examples.

Inertial Frame of Reference

Now, let us understand the inertial frame of reference in detail. The following section provides a detailed description for the inertial frame of reference.

Example of Inertial Frame of Reference

Non-Inertial Frame of Reference

Example of Non-Inertial Frame of Reference

Difference Between Inertial and Non-Inertial Frame of Reference

Inertial Frame of Reference

Non-Inertial Frame of Reference

Moves at a constant velocity (can be zero).

Bodies move at variable speeds

Follows Newton's law.

Newton's law is not obeyed.

bodies do not accelerate.

The body experiences acceleration

The force acting on the body is the actual force.

Acceleration of frames creates a pseudo force

Example: A rocket in intergalactic space (a space without gravity between galaxies) with the engine turned off.

Example: If the car has just started moving from a standstill, the car is in the non-inertial coordinate system during acceleration.

Summary

A frame of reference is required to measure various quantities such as displacement, velocity, and acceleration. A reference frame is an abstract coordinate system whose direction, origin, and scale are specified by a set of geometric reference points whose positions are mathematically and physically identified. A reference frame connected to an object that is stationary or moving at a constant speed is called an inertial reference frame. In the inertial reference system, Newton's first law of motion is applied directly. A coordinate system to which Newton's first law of motion does not apply directly is called a non-inertial coordinate system. In this case, we use pseudo-forces to test Newton's first law.