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Because a difference in position is required when employing the Law of Change for the One-Dimensional Motion with Constant Velocity model, it is important to carefully consider the problem statement, define a useful coordinate system, and accurately assign the initial and final positions. The arbitrariness of choice of origin and direction in the selection of coordinates is a feature of all the motion models that can often be exploited to simplify calcuations, but it is important to remember that with great power comes great responsibility: failing to consider your consciously choose a coordinate system can lead to sloppy math and an incorrect solution.
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