Graphing motion
- 2. Describing a journey made by an object is very boring if you just use words. As with much of science, graphs are more revealing. Plotting distance against time can tell you a lot about a journey.
- 3. Let's look at the axes:
- 4. Time always runs horizontally (the x-axis). The arrow shows the direction of time. The further to the right, the longer time from the start.
- 5. Distance runs vertically (the y-axis). The higher up the graph we go, the further we are from the start.
- 6. If something is not moving, a horizontal line is drawn on a distance-time graph. Time is increasing to the right, but its distance does not change. This graph shows an object that is stationary.
- 7. If something is moving at a steady speed, it means we expect the same increase in distance in a given time. Time is increasing to the right, and distance is increasing steadily with time.
- 8. This graph shows an object that moves at a steady, constant speed.
- 9. Both the lines below show that each object moved the same distance, but the steeper yellow line got there before the other one. What does this indicate?
- 10. A steeper slope indicates a larger distance moved in a given time. In other words, higher speed. This is shown in yellowyellow.
- 11. YellowYellow: speed = distance / time = 30 m / 10 s = 33 m/sm/s BlueBlue: speed = distance / time = 20 m / 20 s = 11 m/sm/s
- 12. For the first part of the journey shown by the graph below, the object moved at a steady (slow) speed.
- 13. Then the object suddenly increased its speed, covering a much larger distance in the same time. The speed increased in the second part of the journey.
- 14. The line below is curving upwards. This shows an increase in speed, since the slope is getting steeper over time.
- 15. In other words, in a given time, the distance the object moves is larger. It is accelerating.
- 16. There are three parts to the journey shown here… Where is the graph showing motion that is: Stopped? Moving at a quick constant speed? Traveling at a slow constant speed? A B C
- 17. The graph below shows several stages of motion: Stage 1: 100 m in 10 s. Stage 2:Stage 2: 50 m in 10 s. Stage 3: 150 m in 20 s. Calculate the speeds of each stage, indicated by the colors.
- 18. The graph below shows several stages of motion: Stage 1: speed = distance / time = 100 m / 10 s = 10 m/s Stage 2:Stage 2: speed = distance / time = 50 m / 10 s = 5 m/s5 m/s Stage 3: speed = distance / time = 150 m / 20 s = 7.5 m/s.
- 19. The graph below shows several stages of motion: Stage 1: constant speed at a relatively high rate Stage 2:Stage 2: constant speed at a relatively slow rate Stage 3: constant speed at a “medium” rate (between the others)
- 20. The graph below shows several stages of motion: The slope of the line (its steepness) indicates rate of change of position. Speed can be estimated by the slope of the line… faster, slower, etc.
- 21. Distance vs. time graphs also indicate the position of the object. Stage 1 & Stage 2:Stage 2: object is moving away from the starting point Stage 3: object is moving back toward the starting point (it comes back to zero)
- 22. The steeper the line on a distance vs. time graph, the faster the object’s speed. A curved line indicates a change in speed (accelerating or decelerating).
- 23. Lines pointing up indicate moving away from the starting location. Lines pointing down indicate moving back towards the starting location.
- 24. Let’s see how much this makes sense to you… This is not for a grade, just to let me know how much of this and what parts of it you “get.”
- 25. To learn about speed vs. time graphs, visit this link: http://www.gcse.com/fm/stg.htm