Inertial frame of reference

An inertial frame of reference is like a playground where we can play different games. To have fun, we need to choose some rules that everyone agrees to follow, like the game cannot be played on the grass or someone cannot touch the ball with their hands.

Similarly, in the physical world, we need to choose some rules that everyone agrees to follow so that we can make accurate measurements and predictions. An inertial frame of reference is a set of rules that everyone agrees to follow for measuring the motion of objects.

For example, we might say that we are standing on the sidewalk, and we see a car coming towards us. We decide that the car's speed is measured relative to our position. This is our inertial frame of reference. However, if we were walking towards the car at the same time, our relative motion would change, and we would need to create a new inertial frame of reference.

An inertial frame of reference follows three main rules:

1. An object at rest will remain at rest, and an object in motion will continue to move at a constant speed and direction, unless a force acts upon it.

2. The laws of physics are the same in all inertial frames of reference.

3. Speed of light is same in all inertial frames of reference.

These rules help us to make accurate measurements and predictions about an object's motion. So, we can say that an inertial frame of reference is like a playground with agreed-upon rules for measuring motion in the physical world.