Hi, I was sitting and thinking of the case where a smoke is rising from say, some incense inside of a car that is accelerating. I thought that it must act the same way as a helium balloon would have. When you turn left, the smoke tends to go left, when you accelerate in a straight line the smoke goes forward etc. I was thinking of the extreme cases where the centripetal acceleration or the acceleration in a straight line is much greater than the acceleration due to gravity if one could treat the cases as if there's no component downwards. Am I thinking of this in the wrong way? It might be more complex than just adding the two accelerations to get a resulting acceleration which leads to a centrifugal force and makes the air and smoke react in other ways than if it were inertial. Let's say in the case that the car has a constant acceleration g both forward and downward.