Conceptual questions regarding motion and vectors

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Please see the attached file.

Since the car travels from east to west, it travels in the negative direction throughout the process. Therefore, the direction of its velocity throughout the process is negative as well. The only graph that reflects this fact is graph C

At the entrance to town, the car experiences a deceleration. This means that the acceleration is pointing to the opposite direction of the traveling direction. Since the car is traveling in the negative direction, the deceleration at the town entrance will be positive. At the town's exit the car accelerates towards the west (the negative direction) and therefore the acceleration there must be also negative.
In between these events, the car maintains a constant velocity which means the acceleration is zero (the acceleration is the change in velocity with respect to time)
Thus graph B is the answer.

In a position graph, the slope of the graph is the velocity. So outside of town the graph's slope will be constant (constant velocity) and negative (the velocity ...