Velocity-Time Graphs
Velocity-Time Graphs is a free interactive simulation for GCSE Physics (Edexcel IGCSE 4PH1). Students pause a car on a preset journey along a flat road, read a speedometer, a timer and roadside distance markers, and plot their own velocity-time graph on paper. No login required.
Timer
0.0 s
Experiment Instructions
- Choose a journey. Press Play and watch the whole journey once without pausing.
- Press Reset. Use Play and Pause, or Step 1 s, to stop the car at different times.
- Each time you stop, read the timer and the speedometer. Add a row and type in both.
- Take readings at least every 2 s, and at every point where the needle changes behaviour.
- Plot speed against time on graph paper.
Results
| Journey | Time / s | Speed / m/s | Actions |
|---|
Aim: To investigate whether the gradient of a velocity-time graph shows how quickly the speed changes, and whether the area under the graph shows the distance travelled.
Part A - First observations
- Before taking any readings, watch Journey A once. Sketch what you think its velocity-time graph will look like. Keep this sketch.
- The road is completely flat. Does the shape of your sketch tell you anything about hills? Explain.
- Watch Journey B. Is there a time when the car is not moving? What does the speedometer show then, and what does the timer do?
Part B - Finding the patterns
- Collect readings for Journey A and plot its velocity-time graph. Compare it with your sketch from Part A.
- For the first section of the graph, how much does the speed increase in each second? Is it the same for every second of that section?
- Find the gradient of that section of your graph. What do you notice when you compare it with your answer to question 2?
- For the section where the line is flat, what is happening to the speed? What is happening to the car's position?
- Find the area between the graph and the time axis for the whole journey. Compare it with the position of the car at the end, read from the roadside markers.
Part C - Explaining formally
- Repeat Part B for Journey C. Which braking section has the steeper gradient? What does this tell you about the car's acceleration in each section? Use the word deceleration in your answer.
- For Journey D, choose two times during the journey. Find the area under your graph between those two times, and compare it with the change in the car's position between them.
- Explain how a velocity-time graph can be used to find (a) the acceleration of a vehicle and (b) the distance it travels. Refer to your own graphs in your answer.
Part D - Evaluation
- Your area for the whole journey and the final marker reading may not match exactly. Suggest two reasons, based on how you took your readings.
- Which of your readings do you think is least precise: time, speed or position? Explain why.
- How could you change the way you took readings to make your graph a more trustworthy measure of distance travelled?