When we are sitting in a train and the train is not moving but a person outside is moving, we feel that the train is moving. This is because of relative velocity between us and the person.
Robert Hooke, an English scientist, gave the Hooke’s Law of elasticity in 1660. It states that for the relatively small deformations of an object, the size of the deformation or displacement is directly proportional to the deforming load or force. With these conditions, the object would return to its original size and shape with removal of the load