You apply the brakes of your car abruptly and your book starts sliding off the front seat. three observers sitting in the car explain this differently. observer a says that the book continued moving and the car accelerated from underneath it. observer b says that the car pushed forward on the book. observer c says that she must be in a noninertial reference frame because the book started moving without any extra objects interacting with it. which of the observers is correct? assume that the car is a frame of reference of all observers.