One- and Two-Dimensional Motion Lab 3

One- and Two-Dimensional Motion
Lab Objectives
• Data collection
• Video analysis
• Linear and nonlinear fitting
• Two-dimensional motion separation
Lab Equipment
• Vernier Motion Detector
• Tall ring stand with horizontal pole
• Racketball
Overview
This lab has two experiments, the first section is about 1D motion and the second about 2D motion. Please excuse
the high number of bullet points in this document!
1D Motion
For this experiment, we will use the Vernier Sonar Ranger to record the motion of a tennis ball bouncing on the
table and analyze the motion.
Procedure
1. Adjust the motion sensor so that the transducer is pointed down and parallel to the bench top. You can
check that it is by making sure a test data collection smoothly shows the distance to the table top.
2. Reverse the direction of the axis for the motion sensor by going to the menu item Experiment > Set
up Sensors > Show all Interfaces as shown in Figure 1. You should see a new window with the
LabPro in the center and your sonar ranger on one side. Select the Reverse Direction option to change
the direction of the axis.
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Figure 1: How to reverse the direction of the motion sensor axis.
a. What happens if you do not do this step? Try it out both ways if you are not sure.
3. Zero the sensor so that the table top will show a distance of zero on the graph. Go to the menu item
Experiment > Zero. . .
4. Set the data collection rate to 31 samples per second as shown in Figure 2.
Figure 2: How to set the data collection rate to 31 samples per second.
5. Drop the ball from 15cm below the sensor onto the table and make sure your data has at least one good and
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complete bounce. This may take a few tries; you can change the position of the switch on the sonar ranger
if you are having trouble getting good data.
b. Why do we need to start the drop 15cm away from the sensor?
6. Identify a region on the graph that show the motion of the tennis ball during one complete trip from the
table surface and back again. Strike through all other data points by selecting the portion of the graph that
we do not want to analyze and use the menu item Edit > Strikethrough Data Cells.
c. Check with your lab instructor to make sure your data is acceptable before you continue.
7. On each graph, right click and select graph options, select the graph options tab, and deselect the Connect
Points box and select the Point Symbols box.
d. Paste your graphs here along with a caption for each one (velocity and position). Read the guidelines below on how to format and write a caption.
The Figures and Captions (Review)
There are a few very important aspects to creating a proper figure and caption. If you follow these rules, not only
will you get points on your physics lab grades, you will impress your instructors and peers in the future.
The Caption
• The caption should start with a label so you can reference the figure from other places in your paper/report.
For this course you should use “Figure 1”, “Figure 2”, etc.
• The caption should allow the figure to be standalone, that is to say, by reading the caption and looking at
the figure, it should be clear what the figure is about and why it was included without reading the whole
paper.
• The caption should contain complete sentences and be as brief as possible while still conveying your information clearly (this is not always easy).
The Figure
• Make sure that the resolution is high enough to not be pixelated at its final size.
• Check that any text is readable at the final size (Using a smaller graph in Logger Pro will cause the text to
be larger in relation to the graph when inserted into another program).
• For graphs, ensure that the axes are labeled (including units) and that there is a legend if you have multiple
data sets on the same graphs.
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Analysis
Velocity Versus Time
1. Perform a linear fit on the velocity graph.
2. Right-click on the box showing the fit information and select Linear Fit Options and check the box
marked Show Uncertainty.
e. What is the slope with uncertainty for this fit?
f. What should the slope represent?
g. Does the result match the known value, within the uncertainty of your measurement? (include
your numbers)
Position Versus Time
h. Based on your knowledge from lecture, what form of equation most closely describes the shape of
the position graph?
3. Perform a curve fit on the position graph using your predicted equation. The dialog box is shown in Figure
3, once you chose the appropriate equation form, use the Try Fit button to see test the fit on your data.
Once you are satisfied that you have the correct equation, you can click Ok to return to your graph with the
new fit overlaid.
Figure 3: Dialog Box for the Curve Fitting feature.
4. Make sure that the fit boxes are not obstructing the data on the graphs and that they are properly formatted
to highlight the important features.
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i. Paste the graphs with the fit parameter boxes here along with new captions that qualitatively describe the goodness of the fits.
Two-Dimensional Motion
5. Open a new Logger Pro file.
6. Add a blank page by going to the menu item Page > Add Page.
7. Insert the movie that is posted on Canvas alongside this worksheet by going to the menu item Insert >
Movie and select basketball shot.mp4 (you will have to download this file to your local computer. If
you wish to reopen the file in the future, you will need the Logger Pro file as well as the movie file).
8. Resize the movie to fit the screen so you can see the basketball.
9. Advance the movie until the ball has left the player’s hand using the frame advance button in the bottom
left corner of the screen ( ).
10. Open the side bar using the button on the bottom right of the movie screen ( ).
11. Using the add point button ( ), mark the center of the ball as carefully as you can. Once you place the
point, the movie will automatically advance one frame and you may place another point.
12. Place points until the ball is at the same height it started; this will be around thirty points.
13. Use the scale tool ( ) to set the scale in the movie. There is a two-meter stick on the floor of the gym in the
movie; select the full distance by clicking and dragging across the meter stick and mark it as two meters.
14. Using the origin tool ( ), mark the first data point you took as the origin.
Analysis
Logger pro automatically splits the motion into separate x and y graphs for you. If you are not sure of what each
graph represents about the motion of the basketball in the movie, please ask your Lab Instructor.
1. Use the curve fit or linear fit to confirm the mathematical shape of each graph.
j. Attach the graphs along with a caption under each using the same format as presented above.
Based on the data that you took today, answer the following questions.
Experimental Method
For the 1D motion experiment, write down with bullet points the five most important steps for your data
collection, including why the particular step is important. Use complete sentences (one per bullet point) not
just a copy and paste of the instructions above.
•
•
5
•
•
•
Results
Write a sentence or two for each question asked below.
1D experiment
1. Using mathematical and physics terms, describe the motion of the tennis ball on the table.
2. What was the velocity and acceleration of the tennis ball, if either value was changing, what were
the limits of the values and what mathematical shape was the graph of those values?
2D experiment
1. Using mathematical and physics terms, describe the motion of the basketball in the movie.
2. For the X direction motion, what was the velocity and acceleration, if either value was changing,
what were the limits of the values and what mathematical shape was the graph of those values?
3. For the Y direction motion, what was the velocity and acceleration, if either value was changing,
what were the limits of the values and what mathematical shape was the graph of those values?
Conclusion Based on your results listed above, what similarities of motion are there in the experiments you
performed? What are the differences?
Graph and Data Checklist You should have six graphs with complete captions and answered all of the questions highlighted by the gray boxes.
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Review
The Figures and Captions
There are a few very important aspects to creating a proper figure and caption. If you follow these rules, not only
will you get points on your physics lab grades, you will impress your instructors and peers in the future.
The Caption
• The caption should start with a label so you can reference the figure from other places in your paper/report.
For this course you should use “Figure 1”, “Figure 2”, etc.
• The caption should allow the figure to be standalone, that is to say, by reading the caption and looking at
the figure, it should be clear what the figure is about and why it was included without reading the whole
paper.
• The caption should contain complete sentences and be as brief as possible while still conveying your information clearly (this is not always easy).
The Figure
• Make sure that the resolution is high enough to not be pixelated at its final size.
• Check that any text is readable at the final size (Using a smaller graph in Logger Pro will cause the text to
be larger in relation to the graph when inserted into another program).
• For graphs, ensure that the axes are labeled (including units) and that there is a legend if you have multiple
data sets on the same graphs.
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