From the above imaginary experiments, Einstein deduced what is called as the 'Principle of Equivalence of Gravitation and Inertia'. This principle states: "It is impossible to distinguish between the motion generated by inertial forces (such as centrifugal force, force producing uniform acceleration) and that by gravitational force."[1]
This is as shown above, due to the fact that the effects of a gravitational field are precisely the same as those due to uniform acceleration of the material frame of reference relative to which the phenomena are observed, this acceleration being equal and opposite to the acceleration which the gravitational field would give to a particle in the frame.[2]