> A decelerating car has negative velocity. not really your point, but ?? a decelerating car has negative acceleration, and until it starts reversing relative

> A decelerating car has negative velocity. not really your point, but ?? a decelerating car has negative acceleration, and until it starts reversing relative to its start, it has velocity in whichever direction it started in -- presumably positive if that was your initial frame of reference. of course if you decided positive was the opposite direction from which the car was already going in, well, it started with negative velocity. also to the GP, if you owe someone a sheep but don't have any, you really do have -1 sheep.