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PHY 121
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Uncertainty Question
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Questions related to Class notes from QA 6
A ball rolls a variety of distances down an incline, from rest, and from a variety of starting positions. The corresponding intervals are timed using TIMER program. All time intervals last at least 1 second and none exceeds 2 seconds. The resulting acceleration values range from 43.2cm/s^2 to 49.6 cm/s^2. According to your experience, what is a reasonable percent uncertainty in measuring these time intervals? Assuming this percent uncertainty, are these results consistent with the hypothesis that acceleration on the incline is independent of position or velocity on the incline?
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I have re-read the section in the textbook about uncertainty. It seems to state that the estimated uncertainty would probably be plus or minus .1. When I used that to figure out the percent of uncertainty, both the high and low numbers came up with .2% percent uncertainty. I figured that this would change 43.2 to 44.06 on the low end. And that the 49.6 would go as low as 48.6, but I don't know if this is correct.
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And, I don't know if the results are consistent with the hypothesis that acceleration on the incline is independent of position or velocity on the incline. I am assuming that the statement means that the ball will accelerate at the same rate and it doesn't matter where it's started or how fast it's going at the measurement points. But I still don't really get what I'm looking for.
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You need to start by estimating the uncertainty in timing an interval between about 1 and 2 seconds.
You've timed intervals not much different from this in the initial timing experiment.
How much uncertainty do you think there is in the timing?
Could that account for the variation in the calculated accelerations?
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