Suppose that all three of the plots shown above describe objects moving on the same coordinate system. The positive direction of the system points east, and the negative points west. Describe the motions of the three objects in words, based upon what you learn from the graphs.
System: The graphs are assumed to represent the motions of objects which can be represented as point particles.
Interactions: Each of the objects must be subject to zero net external force, since their velocities are constant (as indicated by the slope of the position versus time graphs.
Model: One-Dimensional Motion with Constant Velocity.
Approach:
There are many ways to describe the motion, but here are some important features. At the beginning of the motion, A and C are both at the same location, while B is 5 meters east of A and C. A begins moving east at 2 m/s, B begins moving west at 2 m/s and C begins moving east at 1 m/s. By the end of the motion (as plotted) A has caught B (at a position 10 m east of where A and C began). A and B are now 20 meters east of C.