Position–Time Graphs
The slope of a position–time graph is velocity.
About this topic
On a position-time graph, the slope at any point is the velocity. A straight sloped line means constant velocity, a horizontal line means the object is at rest, and a curve means the velocity is changing. A steeper line means a greater speed, and a negative slope means moving back toward the origin.
To find velocity, pick two points on a straight section and compute rise over run, which is change in position divided by change in time. For a curve, draw a tangent line at the instant you care about and find its slope. Where the graph crosses the time axis, the object is passing the origin.
Example: a graph that goes from 0 m to 20 m in 5 s has a slope of 4 m/s. If it then runs flat for 3 s, the object has stopped, and if it then slopes back down to 0 m, the object is returning home. Motion sensors in physics labs and fitness trackers plot exactly such graphs.
Tip: do not confuse the graph shape with the path travelled. A hill-shaped line on a position-time graph does not mean the object climbed a hill; it means the object moved away and then came back. Always read the axis labels before interpreting anything.
Key ideas
- Steeper means faster
- Flat means at rest
- Curves mean changing velocity
Quick check
Use cases: where Position–Time Graphs helps
- Homework: review the key idea behind Position–Time Graphs before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Position–Time Graphs without notes.
- Visual learning: play with the interactive lab to see how Position–Time Graphs changes when you adjust its inputs.
- Teaching a friend: explain Position–Time Graphs 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 Position–Time Graphs?
The slope of a position–time graph is velocity.
What will I learn in Position–Time Graphs?
Steeper means faster. Flat means at rest. Curves mean changing velocity.
Is Position–Time Graphs 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 Position–Time Graphs 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 Position–Time Graphs?
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.