Negative Acceleration

This Friday, my friend drove me back to school after going to the beach. We were in the parking structure going up a ramp to floor 3a or something like that. As we were going up the ramp another car was coming down and my friend had to slow to a stop. After the car had passed she let go of the brake and the car started to roll backwards for a fraction of a second before she stepped on the accelerator. During those couple of seconds, while we slowed to a stop then rolled backwards, we were experiencing negative acceleration. We were going up the ramp in a positive direction, but we were slowing down, then we were going a little faster in the backwards direction. This is somewhat like the toy car experiment in class where the car was pushed up the slanted table. The toy, just like my friend’s car, went up at a decreasing speed, then down at and increasing speed.