A passenger in a moving bus with no windows notices that a

Solution 9DQ Two possible explanations for the given situation are as follows. 1. The bus starts accelerating suddenly. In this case, due to the inertia of rest the ball tends to remains in its initial position. Hence it reaches the rear of the bus when the floor of the bus gets accelerated. 2. The bus starts moving up in an inclined plane. The bus has to do this against the gravitational force and the ball therefore will move downward the inclined plane of the bus.