Distance
Distance is the total length of the path travelled by an object, regardless of direction. It is a scalar quantity, meaning it has magnitude only and is always non-negative. Distance differs from displacement because it tracks the entire route rather than the straight-line separation between start and finish.
Everyday examples comparing distance and displacement
| Scenario | Distance travelled | Displacement |
|---|---|---|
| 400 m lap on a track (back to start) | 400 m | 0 m |
| Walk 3 m east then 4 m north | 7 m | 5 m (NE) |
| Drive 10 km and return halfway | 15 km | 5 km |
| Pendulum swings back to start | Arc length × 2 | 0 m |
| Straight-line sprint of 100 m | 100 m | 100 m |
Interactive Tools
Khan Academy — Distance vs. Displacement
Clear video distinguishing scalar distance from vector displacement
Open ToolPhET Moving Man Simulation
Observe how distance accumulates while displacement may stay small
Open ToolBrilliant — Kinematics Course
Conceptual and problem-based coverage of distance and kinematics
Open Tool
Wikimedia Commons, CC BY-SA
Related Terms
Displacement
Displacement is the shortest straight-line distance between an object's initial and final positions, measured as a vector quantity with both magnitude and direction. Unlike distance, displacement does not account for the actual path taken, only the net change in position. It is the fundamental quantity used to define velocity and is measured in metres (m).
Speed
Speed is the rate at which an object covers distance, defined as the total distance travelled divided by the time taken. It is a scalar quantity, possessing magnitude but no direction, and is always non-negative. Average speed is useful for describing overall motion, while instantaneous speed gives the speed at any particular moment.
Position
Position is the location of an object in space relative to a chosen reference point, described by a set of coordinates. It is a fundamental concept in mechanics because all motion is defined as a change in position over time. In one dimension, position is typically denoted by x and measured in metres from the origin.
From Latin "distantia" (a standing apart), from "distare" — "di-" (apart) + "stare" (to stand). Used in English from the 14th century and adopted into natural philosophy to quantify path length.