The Basic Idea

The slope of a  position-time graph is equal to the velocity of the object. The steeper that a line is (whether sloping up or sloping down), the greater the velocity of the object.
 

There are three very similar versions of this question. Each version provides three lines on a position-time graph, each with a different slope. The question asks the learner to rank the three objects in order of increasing speed. One of the versions is shown below.

Version 1
The motions of Objects A, B, and C are represented on a position-time graph. Observe their lines and rank the speeds of Objects A, B, and C from slowest to fastest.


 

How to Think About This Situation

In this question you have to inspect the three lines on the graph and rank the speeds of the object from smallest to middlest to greatest. The slope of the line on a position-time graph is the velocity. So this question involves comparing the slopes of the three lines. All lines slope upward so the one that slopes most steeply represents the fastest-moving object (greatest speed). The line that is most gently sloped (closer to the horizontal) is the slowest-moving object (smallest speed).
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Try the links below to our Tutorial for more information about position-time graphs:

The Meaning of Shape for a p-t Graph

The Meaning of Slope for a p-t Graph

Determining the Slope on a p-t Graph

 


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