Abbott, David

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State University of New York College at Buffalo - Buffalo State CollegeDigital Commons at Buffalo StateHandouts Physics Labs Using iPads2016Yoyo Lab (In-lab)David AbbottBuffalo State College, abbottds@buffalostate.eduFollow this and additional works at: http://digitalcommons.buffalostate.edu/iphandoutsPart of the Physics CommonsThis Article is brought to you for free and open access by the Physics Labs Using iPads at Digital Commons at Buffalo State. It has been accepted forinclusion in Handouts by an authorized administrator of Digital Commons at Buffalo State. For more information, please contactdigitalcommons@buffalostate.edu.Recommended CitationAbbott, David, "Yoyo Lab (In-lab)" (2016). Handouts. Paper 4.http://digitalcommons.buffalostate.edu/iphandouts/4Date: _____ Yoyo Lab Name: __________________  In-lab instructions and student notes  pg. 1 of 5 The big question(s)  How can you figure out the moment of inertia of an unwinding spool from a video?   Is the value the same as what you could calculate by using just a ruler and a scale? Procedure 1. Make the video of the motion using Vernier’s Video Physics app on the iPad. Some suggestions for making video that’s easy to analyze follow. Make sure that  the yoyo shows up well against the background  the iPad camera is stationary  the iPad is held parallel to the yoyo (You may need to prevent the yoyo from twisting as it descends)  the yoyo’s motion fills a majority of the screen (use iPad in landscape orientation)  there is a dot on the edge of the yoyo so you can count rotations as the yoyo unwinds  you release the yoyo after you begin recording 2. Open up Video Physics and view your video. Check to make sure it’s good enough for analysis. Is the object clear (not blurry)? Is the center of the yoyo clearly visible in most frames? Is the mark on the yoyo you made to count rotations clearly visible? Did the yoyo remain parallel to the iPad as it descended? Is the yoyo’s descent is mostly vertical and in a straight line? (Depending on how release the yoyo, it might wobble around some- that’s bad). If your video isn’t good, now’s the time to reshoot it.  3. Once you think your video is good enough, it’s time to track/mark the motion of the object using Video Physics. The object you will mark/track is the center of the yoyo. Strategic data collection is key for this lab- Video Physics has no way to track the orientation of the yoyo. Here are some recommendations: a) Track/mark the center a few frames before the yoyo is released. On paper (or in your brain), note the location of the dot at the edge (so you can count rotations). b) Track/mark the first few frames at the beginning of the motion. After that, only mark the location of the yoyo’s center when the edge dot passes its original orientation. (This is to make it easy to count how many complete rotations has made just by looking at your graph). 4. Use the software to mark the length of your reference object. Use the radius of the yoyo’s body as your reference object. Measure the radius with a meter stick. Use the software to enter this information.   5. Adjust the axes so that the motion of the object is along the y-axis. Check your graphs in Video Physics to make sure that x-velocity and x-acceleration are both zero throughout the motion. (If not, adjust your axes slightly and recheck).  radius of yoyo = ________________ (don’t forget units) Date: _____ Yoyo Lab Name: __________________  In-lab instructions and student notes  pg. 2 of 5 6. Check the quality of the graphs. Do the graphs show a consistent trend? Is there enough data in all parts of the graph? If not, now’s the time to add those data points (if you skipped them during the tracking process).  7. Measure the mass of the spool and record it here:  8. If you think the data is good enough, it’s time to analyze the data using Graphical Analysis on the iPad. (To export the data to GA from VP, click the share icon at upper right, choose “data file”, “open in…” and “copy to Graphical Analysis”) 9. In previous iPad labs, you used the “fitting” tools. You clicked-dragged to select a section of a graph you wanted to fit and interpreted the fit equation. In this lab, this won’t be very helpful. You will more often want information about individual data points. Instead of click-dragging, simply click on the point you want to know about. You will also find it useful to change the appearance of the graph from “line” to “points.” 10. The main data you want to get off the video is Δ𝑦 the distance the yoyo descended from where it was released 𝑣 The speed of the yoyo has once it has descended a distance Δ𝑦 𝑁 The number of rotations the yoyo made as it descended Δ𝑦 Use a data point near the end of the video as your “final” moment and a data point just before release as the “initial” moment. Record the data below, along with a short description* of how you used the software to determine each: (*Which graph did you consult? Which data point(s)?) Quantity Value (w/ units!) Short description of how you found the value Δ𝑦      𝑣    𝑁     mass of yoyo = ________________ (don’t forget units) Date: _____ Yoyo Lab Name: __________________  In-lab instructions and student notes  pg. 3 of 5 11. Use the data to calculate the radius of the yoyo’s axle. Show your work. Check to make sure your answer is reasonable (i.e. matches what you can “eyeball”).  12. Use the data to calculate the moment of inertia of the yoyo. Show your work.  Use video data to calculate radius of yoyo’s axle: (Show your work) Use video data to calculate yoyo’s moment of inertia: (Show your work) Date: _____ Yoyo Lab Name: __________________  In-lab instructions and student notes  pg. 4 of 5 13. It is also possible to calculate the moment of inertia of the yoyo without the video if you know its dimensions and mass. Use the space below to calculate the moment of inertia, based only on its dimensions. (Hint: Ignore the inner axle- it contributes almost nothing to the overall moment of inertia of the yoyo).  14. The yoyo’s axle has a mass of roughly 10 grams and a radius of roughly 1 cm. Calculate its moment of inertia, based on these dimensions.   Calculate yoyo’s moment of inertia without using video data: (Show your work) Calculate moment of inertia of yoyo’s axle: (Show your work)     What fraction of the yoyo’s overall moment of inertia is due to the axle? Based on your answer, comment on the effect of ignoring the axle’s contribution to the overall moment of inertia. Date: _____ Yoyo Lab Name: __________________  In-lab instructions and student notes  pg. 5 of 5 15. You measured the moment of inertia of the yoyo in two different ways: using video and from its dimensions. Record the results below:  Based on video data: 𝐼𝑦𝑜𝑦𝑜 = Based on dimensions: 𝐼𝑦𝑜𝑦𝑜 = Are these values for 𝐼𝑦𝑜𝑦𝑜 similar? (Calculate a % difference before answering this question).        Should the two values of 𝐼𝑦𝑜𝑦𝑜 be similar? Why or why not? 

Yoyo Lab (In-lab)

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Yoyo Lab (In-lab)

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