Mission KC2 Distance and Displacement
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A teacher does the following:
i. walks 2 m, southii. walks 4 m, east
iii. walks 2 m, north
iv. walks 4 m, west.
The overall displacement of the teacher is ____.
Displacement is a vector quantity which is always conscious of the direction of motion and any changes in that direction. Distance is a scalar quantity which is ignorant of the direction of travel and any changes in direction. Suppose that a person walks 12 meters, east and then 4 meters, west. The distance traveled is 16 meters. The displacement of the object is 8 meters, east. The fact that there is a direction change must be considered when measuring the displacement. Displacement must account for the fact that the 4 meter segment of the motion was in the opposite direction of the 12 meters. For the displacement measurement, the 4 meters is considered as a negative (a directional adjective) and added onto the +12 meters.
In this question, the motion can be broken into four separate parts. To assist in visualizing the situation, it is always a wise idea to construct a diagram. On a piece of scrap paper, pick a starting point and label it start. Sketch out the four parts of the motion using lines with arrowheads. North would be up on the page (using the customary map convention). East would be to the right on the page; west is left and south is down. As you draw, think about the motion - the length of each part of the motion and how the overall position is changing from the labeled starting position.
