This week I performed a guided inquiry activity for the question "Which pendulum will come to rest more quickly—a lighter pendulum or heavier pendulum?" My materials were three different sized washers, one nylon string measuring one meter long, a dowel rod, a stopwatch and a meter stick. After considering how mass affects momentum and researching about pendulums, I hypothesized that the washer with the smaller mass would come to rest more quickly than the washer with the largest mass.
Next I wrote the following procedure. Tie one end of the nylon string to a washer and the other end to a dowel rod. Measure the length of string between the rod and washer. Hold the dowel rod horizontally and pull the washer to a 45 degree angle. Let go of the washer and time the amount of time until the washer comes to rest. Complete three trials with each washer. Test all three washers using the same length of string and angle of release.
After conducting the inquiry activity, I found that each washer came to rest at an average of 28 seconds, so I concluded that mass does not affect the period of vibration (Communications, n.d.). Although these are not the results that I expected, the proof was in the inquiry.
If I was to perform this inquiry again I would change one of the controls like the length of string and redo the experiment to see if the results are the same even if the string was longer or shorter. I would also do more than three trials to get a more exact average.
In my classroom, I could set up this exact experiment allowing the students to select the bob(weight) for their pendulum and have the students graph their results(Communications, n.d.). The graphs could then be compiled to look for a best fit line. To make this activity more interesting and relevant, I could take the students down to the elementary school playground and use the swings as the pendulum and different students as the bobs.
I would like the students to learn that mass does not affect the period of vibration for a pendulum which coincides with what Galileo concluded about mass not affecting how long it takes an object to free fall to the ground when dropped (Tillery, Enger, & Ross, 2008).
Communications. (n.d.). Howstuffworks "Pendulum". Howstuffworks "Science". Retrieved May 16, 2010, from http://science.howstuffworks.com/pendulum-info.htm/printable
Tillery, B. W., Enger, E. D., & Ross, F. C. (2008). Integrated science (4th ed.). New York: McGraw-Hill.
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P - Nice work! You should check out Donna's blog. You did similar inquiries but had different outcomes. I think the main difference might have been the height at which you dropped from. The two of you make me want to try the pendulum inquiry!
ReplyDeleteP- I tried this experiment. I measured and dropped my washers from a 45 degree angle also. My results show the time differences almost 3 minutes apart. Did you stop timing when they where hanging and extremely slow? I was able to measure mine for a long time at the bottom with minute momentum by lines in the wood floor. What did you do with the dow rod? Did you hold it in your hand? That could be a second variable. I placed the broom handle across two chairs. Please respond on my blog. Thanks for the interaction and communication.
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ReplyDeleteP- I tried this experiment. I measured and dropped my washers from a 45 degree angle also. My results show the time differences almost 3 minutes apart. Did you stop timing when they where hanging and extremely slow? I was able to measure mine for a long time at the bottom with minute momentum by lines in the wood floor. What did you do with the dow rod? Did you hold it in your hand? That could be a second variable. I placed the broom handle across two chairs. Please respond on my blog. Thanks for the interaction and communication.
ReplyDeleteI had a different result. I had my hypothesis backward; however, my washer with the most mass swung longer. It had small momentum but monmentum non the less.
ReplyDeleteSorry. When I pull up your blog I don't seem to find my post until I have posted again. Can you see them when you pull it up?
ReplyDeleteDonna
ReplyDeleteYes I see all of your posts. Maybe you need to refresh to see your posts?
B
ReplyDeleteI was surprised that Donna's results were different from mine. I have one more day of school and two days of cleaning and then I am planning to redo the experiment and see if my results are the same.
Sorry this is late. I did not understand what I was doing. Both you and Donna had different results, but learned alot about momentum. This is what teachers need to express to students about science experiments. Sometimes they work and sometimes they do not. It is the process that is important, as well as evaluating how to make it better the next time.
ReplyDeleteMelva
ReplyDeleteThank you for the reminder that the results are not as important as the process and learning along the way. I get as wrapped up in the results as my students do.