Distance and Displacement Edit
Distance and displacement are two quantities that seem to be the same thing but that have different meanings.
Distance is a scalar quantity that shows how much ground an objects has traveled during its motion. Distance is a scalar therefore it has a magnitude and it is one dimensional.
Displacement on the other hand, is a vector quantity that measures how far the object moved from its original place. Displacement is a vector therefore it has a magnitude and it also has a direction and it is two dimensional.
Example: chesse head
If a boy walks 4 meters East, 2 meters South, 4 meters West, and finally 2 meters North.
Even though the boy has walked a total distance of 12 meters, his displacement is 0 meters. During the course of his motion, he has "covered 12 meters of ground" (distance = 12 m). Yet when he is finished walking, he is not "out of place" - i.e., there is no displacement for his motion (displacement = 0 m). Displacement, being a vector quantity, must give attention and regard to direction. The 4 meters east is canceled by the 4 meters west; and the 2 meters south is canceled by the 2 meters north.
With this we can see the difference between distance and displacement and understand their meaning and their use. Distance is the absolute value of the displacement. Distance is always positive.
Units are important in Physics. We will usually measure distance or displacement in units of meters (m). Distance or displacement could also be measured in centimeters (cm) or kilometers (km) or even miles (mi).
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