[NOTES/ME-08009]-How good is a frame as inertial frames

1. Inertial and Non inertial frames

The Newton's laws are applicable in an inertial frame. In order to describe the motion of a body from a non inertial frame, suitable pseudo forces must be added to the external forces. before applying Newton's laws. The pseudo forces are dependent on the acceleration, hence the acceleration of a frame can be measured by performing a mechanical experiment entirely within the frame of reference. We take up a few examples of this and see which frame of reference can be described as a very good inertial frame. The pseudoforces share an important property with the gravitational forces. Both are proportional to the mass. Conceptually the mass appearing in the second law and in pseudo forces is different from the mass appearing in the gravitational pull exerted on a body by another body. The experimental equality of these two unrelated concepts, --- the inertial and the gravitational mass ----