Understanding Motion Graphs: Position-Time & Speed-Time

1. 1-3 Notes – Graphing Motion Chapter 1 Lesson 3

2. Graphs • Graphs often show how something changes with time. • This graph shows how temperature changes with time in Santa Barbara, California.

3. Position-Time Graphs • Time goes on the x-axis. • Position goes on the y-axis.

4. Position-Time Graphs • The table shows how far a turtle moves every 20 seconds.

5. Plot the time on the x-axis. Time (s)

6. Plot the distance the turtle has moved on the y-axis. Position (cm) Time (s)

7. Now, plot each point.

8. Now, plot each point.

9. Now, plot each point.

10. Now, plot each point.

11. Now, plot each point.

12. Now, plot each point.

13. Now, plot each point.

14. Because it’s a straight line, you can use it to estimate the turtle’s position at other times. 120 ?

15. Because it’s a straight line, you can use it to estimate the turtle’s position at other times. 120 ?

16. Because it’s a straight line, you can use it to estimate the turtle’s position at other times. 120 246

17. Position-Time Graphs • The steepness of a line on a graph is called the slope.

18. Position-Time Graphs • The slope of the line on a position-time graph tells you speed (distance ÷ time). • Slope = rise ÷ run

19. Position-Time Graphs • The steeper the slope of the line, the faster the object was moving. (red) • The flatter the slope of the line, the slower the object was moving. (green)

20. Position-Time Graphs • To find the slope of a line, pick 2 points along the line. • Use the origin (0,0) and another point (x,y).

21. Position-Time Graphs • The “rise” is the change along the y-axis (how high the line rises). rise (distance) run (time) rise (cm)

22. Position-Time Graphs • The “run” is the change along the x-axis (how far the line runs). rise (distance) run (time) run (s)

23. Position-Time Graphs

24. rise run slope = Position-Time Graphs

25. Position-Time Graphs • A linear position-time graph (straight line) means the object does not change speed. It moves at a constant speed.

26. Position-Time Graphs • A nonlinear position-time graph (crooked line) means the object does change speed.

27. Position-Time Graphs • To find the average speed of the entire trip, use the starting and ending points to calculate the slope.

29. Speed-Time Graphs • Constant speed on a speed-time graph is a horizontal line because the speed does not change.

30. Speed-Time Graphs • If an object speeds up, its line on a speed-time graph curves up to the right. The steeper the slope, the faster its speed is increasing.

31. Speed-Time Graphs • When an object slows down, its line on a speed-time graph slopes down to the right.

32. Speed-Time Graphs • The slope of the line on a speed-time graph tells you acceleration (speed ÷ time) rise (speed) run (time)

33. 1.3 Graphing Motion The horizontal change on a graph is also called the ____. A rise B elevation C run D distance

34. 1.3 Graphing Motion The steepness of a line on a graph is called the ____. A slope B hill C rise D run

35. 1.3 Graphing Motion If the rise is equal to 75 m and the run is equal to 2.5 m, then what is the slope? A 187.5 m B 12 m C 30 m D 0.03 cm

36. Describe a position-time graph of an object moving at 10 km/h. A upward slant to the right B horizontal line C upward slant to the left D none of the above