Question

What are inertial and non-inertial frames of reference?

Answer 1

An inertial frame of reference is a frame of reference in which bodies, whose net force acting upon them is zero, are not accelerated, that is they are at rest or they move at a constant velocity in a straight line. Newton's laws of motion hold true in an inertial frame. A frame of reference that moves with constant velocity with respect to an inertial frame is also an inertial frame.

A frame of reference which is accelerated with respect to an inertial frame is known as a non-inertial frame.