PASCO SE-9076 Constant Velocity Tubes - Manual (Page 15)

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Constant Velocity Tubes 012–06697B
5. Choose other lengths of time between these two extremes. Enter the data into the data
table. Plot the points as you go and examine the pattern as it forms. Choose additional
times to try based on missing parts of the pattern. Be on the lookout for obvious mistakes as
you plot the points. Do not rush to throw out any of your data, though.
6. Draw a best-fit line though your data. A straight line drawn with a ruler should do a good
job of representing the pattern of the data. If it does not, ask your instructor for advice.
➤ If time permits, improved accuracy can be obtained by repeating a time
more than once and plotting the average position for that length of time.
7. If necessary, extend your line until it meets the vertical axis. What is the value of the y-
intercept? ___________________ (Don’t forget units of measurement.)
8. What is the meaning of the y-intercept? (Not the mathematical meaning, but the meaning
in terms of the details of this experiment.)
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9. Unwrap the paper from the tube and examine the tube. Measure from the bottom of the
tube to the place where the bottom of the bubble started. (If the bubble started somewhere
under the black end cap, you may estimate its starting position at 1 cm.) Record this
measurement:
____________________
Replace the wrapping.
10. Compare your results for steps 7 and 9 above and comment:
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11. Some of the tubes in the set have bubbles that travel at essentially the same speed as the one
you just worked with. Others travel at a dramatically different speed. Choose a tube of a
different color, but with a speed that is essentially the same as the one you used before.
Take time and position data for this tube, and enter it into a new data table, but plot the
points on the same graph you used before. Draw a best-fit line for this data, too.
12. Compare the best-fit lines from the two tubes for similarities and differences. Try to explain
the reasons for them. Unwrap the paper from the second tube to verify your explanation.
Replace the wrapping.
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