Distance Versus Directed Distance and Displacement
Distance cannot be negative and distance travelled never decreases. Distance is a scalar quantity or a magnitude, whereas displacement is a vector quantity with both magnitude and direction.
The distance covered by a vehicle (for example as recorded by an odometer), person, animal, or object along a curved path from a point A to a point B should be distinguished from the straight line distance from A to B. For example whatever the distance covered during a round trip from A to B and back to A, the displacement is zero as start and end points coincide. In general the straight line distance does not equal distance travelled, except for journeys in a straight line.
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Famous quotes containing the words distance and/or directed:
“It is the simplest relation of phenomena, and describes the commonest sensations with more truth than science does, and the latter at a distance slowly mimics its style and methods.”
—Henry David Thoreau (1817–1862)
“Life is an offensive, directed against the repetitious mechanism of the Universe.”
—Alfred North Whitehead (1861–1947)