Distance and Displacement
Distance is the path length; displacement is the straight-line change in position.
About this topic
Distance is the total length of the path travelled, a scalar that only grows. Displacement is the straight-line change in position from start to finish, a vector with direction. Run once around a 400 m track and your distance is 400 m but your displacement is zero, because you finished where you started.
This difference matters because velocity and acceleration are defined using displacement, not distance. Displacement is found as final position minus initial position, and its sign tells you the direction along a line: positive might mean east or right, negative west or left. Distance is always zero or positive and can never be less than the size of the displacement.
Example: a student walks 3 m east, then 5 m west. The distance travelled is 8 m, but the displacement is 2 m west, or minus 2 m. GPS apps report distance for your trip, while a bird flying home in a straight line cares about displacement. Surveyors and navigators use both ideas all the time.
Tip: when a question says how far did it travel, think distance; when it says how far from the start or where did it end up, think displacement. Many students wrongly assume the two are equal, which is only true for straight-line motion in one direction.
Key ideas
- Displacement can be zero after a round trip
- Distance is never negative
- Displacement includes direction
Quick check
Use cases: where Distance and Displacement helps
- Homework: review the key idea behind Distance and Displacement before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Distance and Displacement without notes.
- Visual learning: play with the interactive lab to see how Distance and Displacement changes when you adjust its inputs.
- Teaching a friend: explain Distance and Displacement in your own words, then compare your version with the key ideas.
The same laws describe car crashes, sports, satellites and everyday machines.
Frequently asked questions
What is Distance and Displacement?
Distance is the path length; displacement is the straight-line change in position.
What will I learn in Distance and Displacement?
Displacement can be zero after a round trip. Distance is never negative. Displacement includes direction.
Is Distance and Displacement part of Physics?
Yes. It is one of 150 Physics topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Distance and Displacement lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Distance and Displacement?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.