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 Tweet # Position vs. Time Graphs Introduction: Stationary, moving more quickly, moving more slowly - all of these expressions can be used to describe changes in the position of an object with time, whether it is a person, an insect, or a sports car. A graph of position vs. time is a graph where position is often plotted on the y-axis and time is plotted on the x-axis, such that motion can be described and - where appropriate - compared to other motion. When looking at plots of position vs. time, motion can be described and understood on the basis of the slope and the overall type of graph that is represented.

In general, with a position vs. time plot, a positive slope for a line means that there is a constant positive velocity, while a negative slope for a line means that there is a constant negative velocity. Any kind of plateau or zero slope for a line on a position vs. time plot would suggest that there is no change in position with time, so the velocity could be assumed to be zero, in these cases. On the other hand, a changing positive velocity would be represented by a curve that travels upwards, suggesting that acceleration is occurring.

In addition to determining whether velocity is changing and to determining the sign of velocity, it is also possible to gauge how fast or slow an object is relatively moving in terms of its velocity. A slow, positive constant velocity could be aptly represented by a line with a positive slope that is not very steep, suggesting that position is not changing very quickly with time. On the other hand, a fast, positive constant velocity would be represented by a line with a positive slope that is very steep, suggesting that position is changing relatively quickly with time.

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