Let's Graph With Probes - nk working version
Focus for this activity
In this activity you will graph motion as it changes over time using
a motion probe that can measure and graph your motion automatically.
It's fun!
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The motion you will study is the trip made by Vijay from the
“Hanging with Friends” story. You will be Vijay and walk his
trip from the Library to the Cinema then back to the Library.
Remember from the story that the Cinema is 7200 meters from the Library. Don’t worry though, you won’t have to move that far! Before you get started with your trip, your teacher will demonstrate how to use the motion probe. You also will have a chance to think about what a graph of motion means and draw a graph by hand that tells the story of Vijay's trip. |
Demonstration
Your teacher will now demonstrate the use of the motion probe.
Watch your teacher's graph during the demonstration, then answer the question below.
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Prediction
One way to graph motion is to plot "position" as it changes over
time. Position is the distance of a location measured from a
definite reference point. The reference point could be any location
that we choose, but once we choose it, it is fixed. We will call
this reference point position 0 and give it the special name of
“origin.”
Now, try drawing a graph that you think predicts how Vijay's position changes over time. Draw a line on the graph below that you think describes his trip. Click on the pencil tool at the right to draw your prediction line. Here is what you need to know to get started:
• The Library is located at the origin, position 0. • The distance between the Library and Cinema is 7200 meters. • Vijay travels from the Library to the Cinema and back to the Library. • The whole trip takes 20 minutes.
After you have drawn your prediction, use the label tool, just below the pencil tool, to mark the positions of the Library and the Cinema on the graph. (Click on the label tool, then click on a location on the graph, and the label will be attached to that location.) When you've finished, submit your graph for anonymous sharing with your teacher and classmates by clicking on the Submit button located below the graph.
Prediction Graph Results
After you have submitted your prediction graph on the previous page,
you will see some of your classmates' graphs below after your
teacher releases them. If the graphs are not visible yet, click the
Refresh button. If they still aren't visible, move on to the next
step and check back later for results.
Reference points
As you have seen, in order to plot position you need a reference
point. For this activity, the reference point is position 0, the
origin. Let's say that the Library is located at the origin.
Vijay starts his trip at the Library then moves to the Cinema, so you also will need to know the Cinema’s position and the direction in which position increases.
For our version of Vijay’s motion we define:
• The Cinema is 1 meter from the Library. • Position increases as we move from the origin toward the probe.
In the next step, you will walk on your masking tape "street" using the motion probe and graph to find the origin. The origin is at a pre-set distance from the probe, and your task is to find that distance.
Find the Library!
How will you find the origin on your street? Try this:
Set up your motion probe at the end of a desk or table just in front of the masking tape “street.” While watching the graph, start the probe and walk along the street in front of the motion probe until you think you've found position 0, stopping and clearing the graph as needed.
Write the word "Library" on a Post-It note and place the note on the "street" at the position of the origin. Then measure the distance from the origin to the probe, and submit your answer to the question below.
After you submit your answer, you'll be able to see the class' answers on the next page after your teacher releases them for viewing.
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Library Location Results
Your class' answers should appear below as a histogram. If they are
not visible yet, click the Refresh button. If they still aren't
visible, move on to the next step and check back later for results.
Your turn!
Without moving your probe or your Library Post-It note, write "Cinema" on a second Post-It note, and place that note at the location of the Cinema. Remember that the Cinema is on the "street" and 1 meter closer to the probe than the Library.
Try walking Vijay’s trip from the Library to the Cinema and back to the Library in 15 seconds. (There's no need to stop the graph yourself; it will automatically stop after 15 seconds.) Try walking the trip several times, each time clearing the previous graph and creating a new one. Try travelling at different speeds, watching the graph to see how different motions are graphed. Then submit your answers to the questions below.
After you submit an answer, you will be able to see the class' answers after your teacher releases them. You will see the answers in a pop-up window that will appear after you click on the Results button.
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Your Trip to the Cinema
Now plan and make a final graph of your trip to the Cinema as Vijay
did. Here is his trip:
• Vijay starts at the Library. • He proceeds to the Cinema. • He returns to the Library. • The whole trip takes 15 seconds.
Start the graph and walk Vijay’s trip. Try walking the trip several times, clearing to erase previous graphs, until you have a graph that matches Vijay's trip and that you are willing to share with the class. Then submit the graph for anonymous sharing by clicking the Submit button below the graph.
After you submit your graph, you'll be able to see some of the class' graphs on the next page after your teacher chooses several and releases them for viewing.
Cinema Trip Results
After you have submitted the graph on the previous page for your
trip to the Cinema, you will see some of your classmates' graphs
below after your teacher releases them. If the graphs are not
visible yet, click the Refresh button. If they still aren't
visible, move on to the next step and check back later for results.
Discussing class graphs
Have a look at the class' graphs projected in front of your
classroom or in the results pop-up window (that appeared after
clicking the Results button at the bottom of the previous page).
Please answer and discuss the following questions. You may change
your answers after the class discussion.
Discussing graphs results
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The End
Motion Probe Demonstration
Your Trip to the Cinema
Now plan and make a final graph of your trip to the Cinema as Vijay
did. Here is his trip:
• Vijay starts at the Library. • He proceeds to the Cinema. • He returns to the Library. • The whole trip takes 15 seconds.
Start the graph and walk Vijay’s trip. Try walking the trip several times, selecting one of the three Data Sets each time by clicking on the Data Set's name. You will end up with three Data Sets on the graph. If you'd like to try more than three times, select a particular Data Set and clear it, then walk the trip again. When you have a Data Set that matches Vijay's trip and that you are willing to share with the class, uncheck the other two Data Sets by clicking on the check mark to the left of their names. One Data Set should remain visible. Then submit the graph for anonymous sharing by clicking the Submit button below the graph.
After you submit your graph, you'll be able to see some of the class' graphs on the next page after your teacher chooses several and releases them for viewing.