Displacement (vector)
In Newtonian mechanics, displacement is one of two subtly different quantities measuring distance and direction.
Image:Distancedisplacement.png
Displacement compared with distance along a path
(a) Displacement in the sense of position vector is a vector quantity which expresses position by the length and direction of a straight line from one place to another (as opposed to the scalar quantity distance which expresses only the length). The SI unit for either distance or displacement is the metre.
(b) Displacement in the sense of movement is a vector quantity which expresses the distance and direction (in a straight line) from the starting to the finishing point.
The two meanings are not the same, as the table shows:
| (a) | (b) | |
|---|---|---|
| Where are you? | displacement | Position |
| Where are you relative to the starting point? | Change of displacement | displacement (= change in position) |
| Velocity | Rate of change of displacement | Rate of displacement |
|
← Antidifferentiate ... Differentiate → |