I was going through my engineering mechanics notes and i have this question in my mind. Suppose there is a system on the ground consisting of spring and mass(m) attached to it. An observer(O) applies a force on the mass which compresses the spring (to the left) and hence the force by the spring on the block makes the block move to the right. The observer(O) will find the block moving to the right and left. But what about an observer(O') who is in an accelerating frame of reference(say on a platform that's rotating).What i feel is he would notice the same thing that the observer O is moving(the mass will move) but if we ask him the question how many times do you think the mass moved left and right. He would answer 'say x' . Because if feel that he missed some of the motion of the mass as he was on a accelerating frame of reference.However the observer O would say it moved 'x+n'. I dont know if i am correct. Please evaluate my concept. **No links please**