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 that has a constant, positive acceleration. 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.


 
As mentioned in the Know the Law section, the slope of a line on a velocity-time graph represents the acceleration of an object. As the slope goes, so goes the acceleration. So if you are trying to find a line that represents a constant acceleration, then you should be looking for a line with a constant slope. A constant slope line is a line that is straight for the entire duration of time. If you are trying to find a line that represents a positive acceleration, then you should be looking for a line with a positive slope. A line with positive slope is sloping upward. If you can put these two ideas about constant acceleration and positive acceleration together, you will be successful on this question.


 
It is not uncommon for a student to confuse velocity and acceleration. On a velocity-time graph, a line with positive velocity is a line that is being plotted above the time axis in the positive region of the graph. A line with a positive acceleration is a line with a positive slope. But don't be fooled! An object can have a negative velocity and still have a positive acceleration. Do not restrict your answers to this question to those lines which are plotted in the positive region of the graph. Simply look for lines with positive slope (and constant slope) - regardless of whether they are above or below the axis.