Kinematic Graphing - Mission KG7 Detailed Help

The motion of six objects - A, B, C, D, E, and F - are represented by lines on a velocity-time graph. Write the letter(s) for any object which is at rest (for the entire motion). List all that apply ... .

 
Velocity-Time Graphs:
Velocity versus time graphs represent changes that occur in an object's velocity with respect to time. The slope of the line is the acceleration (change in velocity divided by the change in time) of the object. The area under the line (between the line on the graph and the time axis) is the displacement of the object.


 
It is not unusual for a student to confuse position-time graphs with velocity-time graphs. They know that being at rest is represented on a position-time graph by a horizontal line with zero slope. So they instantly begin looking for the same line on this graph. But don't be fooled! This is a velocity-time graph and a horizontal line is a line with 0 acceleration. A moving object could be represented by a horizontal line on a velocity-time graph is if it is moving with a constant velocity.


 
This is an example of a question that can be answered with a mixture of good math sense and logical thinking. The graph is a plot of velocity. An object that is at rest has a velocity of 0 m/s. Thus, an object that is at rest (not moving) is represented by a horizontal line that lies along the time axis at a velocity value of 0 m/s.