[NOTES/ME-08010]- An Example

If we have an accelerated frame of reference, like an accelerating elevator a car or train, a non zero acceleration of the frame can be detected by doing a mechanical experiment entirely within the elevator or the car or the train without need for looking outside.This is possible because the equations of motion take different forms in differently accelerating frames. So for example a weight attached to a spring balance and hung from ceiling of an moving lift will show different pointer positions for different accelerations. A pendulum in an car or a train moving with uniform velocity will hang vertically down. If the car is accelerating it will not be hanging vertically down, but the string will be tilted backwards.