But if the rotor has got no initial rotation, situation is quite different. North Pole of the Rotor will obviously get attracted by South Pole of RMF, and will start to move in the same direction. But since the rotor has got some inertia, this starting speed will be very low. By this time South pole of RMF will be replaced by a North pole. So it will give repulsive force. This will make the rotor move backward. As a net effect the rotor won’t be able to start.