Displacement
The straight-line change in position from start to finish, with a direction. It ignores the path you took.
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Analogy
Like a bird's-eye arrow from your front door to where you ended up.
Example
East 3 m, north 4 m.d = sqrt(3^2 + 4^2)d = 5 m, north of east.
In practice
Walk 3 m east, then 4 m north. You walked 7 m but your displacement is 5 m.
Practice
Flashcards
- Can displacement be smaller than distance travelled?Yes. Displacement is the straight line from start to end, distance is the path length.
Questions people ask
Is displacement a vector or a scalar?
Displacement is a vector. It has a size, such as 5 m, and a direction, such as north of east. Distance travelled is a scalar because it has size only. The two match only when you move in a straight line without turning back.
Can displacement be zero if I walked a long way?
Yes. If you finish exactly where you started, your displacement is zero, even after a long walk. A full lap of a running track is a good example. You covered about 400 m of distance but your overall change in position is zero.