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You’re driving along the highway at 60 mph until you enter a town where the speed limit is 30 mph. You slow quickly, but not instantly, to 30 mph. Draw a basic motion diagram of your car, using images from the movie, from 30 s before reaching the city limit until 30 s afterward.

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Solution:

Model

We will assume that the term “quickly” used in the problem statement means a time that is short compared to 30 s.

Solve

Assess

Notice that the acceleration vector points in the direction opposite to the velocity vector because the car is decelerating.

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