Question

Pls difference inertial and non inertial frame @ParthKohli

Answer 1

@inkyvoyd

Answer 2

In an inertial frame, Newton's first and second law hold.
In a non-inertial frame, it will hold only if you add ad-hoc defined inertial forces, depending on the relative motion of the non-inertial frame with respect to the inertial one.

It may seem a pointless at first, but those inertial forces also behave like actual forces when working out their moments (torques), works etc.
Solving problems of moving objects in rotating frames for instance becomes much simpler this way.

Answer 3

non inertial frame is moving and is not at rest whereas inertial frame is at rest :)