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 has a constant, negative 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 line of constant slope is a line that is straight for the entire duration of time. If you are trying to find a line that represents a negative acceleration, then you should be looking for a line with a negative slope. A line with negative slope is sloping downward. If you can put these two ideas about constant acceleration and negative 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 negative velocity is a line which is being plotted below the time axis in the negative region of the graph. A line with a negative acceleration is a line with a negative slope. But don't be fooled! An object can have a positive velocity and still have a negative acceleration. Do not restrict your answers to this question to those lines that are plotted in the negative region of the graph. Simply look for lines with negative slope (and constant slope) - regardless of whether they are above or below the axis.