Graphing Motion
Define Position: Describes the location of object relative to a reference point Reference Point: A starting point used to describe the position of an object Distance: a measurement of the amount of space between two objects Speed: the distance an object moves over a given time period (the rate at which an object is moving)
Graphs Graphs often show how something changes with time. This graph shows how temperature changes with time in Santa Barbara, California.
Position-Time Graphs Time goes on the x-axis. Position goes on the y-axis.
Position-Time Graphs This table shows how far a turtle moves every 20 seconds.
Plot the time on the x-axis. Time (s)
Plot the distance the turtle has moved on the y-axis. Position (cm) Time (s)
Now, plot each point.
Now, plot each point.
Now, plot each point.
Now, plot each point.
Now, plot each point.
Now, plot each point.
Now, plot each point.
Because it’s a straight line, you can use it to estimate the turtle’s position at other times. 120 ?
Predict the turtle’s position at 120 seconds. ?
120 ?
The turtle will be at 246 cm at 120 seconds.
Position-Time Graphs The steepness of a line on a graph is called the slope.
Position-Time Graphs rise run slope =
Position-Time Graphs What is the relationship between the slope and speed of an object on a position-time graph?
Position-Time Graphs Plot the second turtle data onto your turtle graph. Use another color! 20 41 60 79 101
Position-Time Graphs 20 41 60 79 101
Position-Time Graphs Speed = distance ÷ time Which turtle had a higher speed? How do you know?
Position-Time Graphs What is the relationship between the slope and speed of an object on a position-time graph?
Position-Time Graphs The slope of the line on a position-time graph tells you speed (distance ÷ time).
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)
Position-Time Graphs (ISN p. 64) Match each graph to the correct description. Be prepared to justify your answers. 1. 2. 3. B) Elizabeth stood still for 4 seconds. C) John ran 30 yards in 4 seconds. A) Charlie ran 20 yards in 2 seconds, then ran back to the starting line.