A Look at the Types of Frame of Reference

In physics, quantities such as velocity and displacement change based on the observer’s point of view or the frame of reference from which the values are observed. Any point in space can be represented in the form of its cartesian coordinates like (x,y,z), where x is the distance of that point from the x-axis on a frame, y is the distance of that point from the y-axis and z is the distance from the z-axis.

In other words, the coordinate system is a way to represent any point or object in 3-D space. A coordinate system can also be called a frame of reference in physics. In the following article, the different types of frames of reference are discussed based on their motion.

The Frame of Reference Definition

A frame of reference can be thought of as one’s own XYZ axis or how one sees the world in relation to themselves. If someone is seated in a car, for example, everything around them is relative to them because they believe they are sitting motionless and stationary although everything around them is moving. However, someone looking from outside the automobile and viewing the person inside would believe that the person is moving along with the car, despite the fact that the person is still. As a result, both people have different points of view. Because motion is decided by the person who observes it, it is referred to as relative motion.

Inertial Frame of Reference

When a person’s frame of reference is moving at a constant velocity or is stationary, it is called an inertial frame of reference. That is, no net force is imparted to a person’s reference frame if they are not accelerating. The rules of physics behave as they should in this situation. It is usually thought that a frame that is at rest or moving with uniform velocity is considered to be an inertial frame of reference and if it is accelerating, then it is a non-inertial frame of reference.

To test whether a frame of reference is purely inertial or non-inertial, it should be noted if any particle in that frame experiences any sort of force or not and whether the particle is accelerated or not. Such a frame of reference is called a purely inertial frame of reference.

Non-inertial Frame of Reference

There are additional forces at work when acceleration is introduced to a person’s frame of reference, normally termed as the non-inertial frame of reference. A person can only realise that they are moving if they are in a non-inertial frame of reference. When a particle is observed from a frame of reference on which there is no force but has some acceleration, such a frame of reference is a non-inertial frame of reference.

On the contrary, if the particle is under some force, but the acceleration is zero, this frame of reference is also non-inertial. Whereas when the particle is under both a force and an acceleration, then too, the frame of reference is non-inertial.

Explanation using an Example

Consider a circumstance in which a person is standing stationary on the ground and measuring the ground’s velocity. The earth serves as the frame of reference here. Because the person is immobile in relation to the ground, the ground seems to have no velocity. Now, if a person standing still were to measure the velocities of a car travelling down the road and an aeroplane flying through the sky, they would have some velocities because both vehicles appear to move.

In the second scenario, the frame of reference is shifted to a moving automobile with a person inside. The individual sitting inside the automobile would believe that the car is motionless while the ground is moving in this case. However, the same person in an aeroplane would appear to be moving quicker.

In the third scenario, the passenger is sitting inside the plane, and the plane is the frame of reference. Because the individual is seated inside the plane, it seems to be stationary in this situation. The ground and the car now appear to be moving from the point of view of the individual.

Conclusion

In the article above, we discussed what a cartesian plane is and what a coordinate system is and who found it. They were then related to a frame of reference. A frame of reference was discussed to be one’s own XYZ axis and as the name suggests, it is used as a reference to position any object or to study its motion. It was said that the frame of reference is of two types: The inertial and non-inertial frame of reference. The inertial frame is one from which a particle is observed and is found to be at rest or at a constant velocity, whereas a non-inertial one is said to experience some kind of force or acceleration. The inertial and non-inertial frame of reference was explained with the help of a real-life example.