Question

what is rest position

Answer 1

The amplitude of a wave refers to the maximum amount of displacement of a particle on the medium from its rest position. In a sense, the amplitude is the distance from rest to crest. Similarly, the amplitude can be measured from the rest position to the trough position

Answer 2

rest is a state of an object in which no external force is applied and there is no change in position with respect to time and surroundings.