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Mission KG9 Graphs and Oil Drop Diagrams - Question Group 1 Help

Match the oil drop representation below to the appropriate letter for a position-time graph. It is known that the object is moving toward the right (where rightward is the positive direction).

NOTE: Some versions of this question show the object moving leftward.

Position-Time Graphs:
Position versus time graphs represent changes that occur in an object's position with respect to time. The slope of the line is the velocity (change in position divided by the change in time) of the object.

The oil drop pattern uses dots to represent the location of the car after a certain interval of time - perhaps after every 1-second interval in time. An inspection of the location of each dot relative to the previous dots allows you to determine if the distance traveled in the most recent second is increasing, decreasing or staying the same. You can decide what type of motion is involved by observing how the distance traveled in each consecutive second is changing.

It should be clear from the oil drop pattern that the object is moving with a constant velocity. In some cases it is a constant positive velocity; in other cases, it is moving with a constant negative velocity. You must match this with the appropriate position-time plot. As mentioned in the Know the Law section, the slope of a position-time graph is equal to the velocity. As the slope goes, so goes the velocity. You will need to find the one line on the graph which has a constant positive (or perhaps negative) slope. A constant slope is characteristic of straight lines; this rules out the four curves.