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course Phy 231
12/07/2011 @ 12:20 a.m.
Truck overtakes car
You used a combination of three tracks to simulate the problem in which a car passes before I pull out in my truck.
Insert a copy of your data here, along with any previously submitted work you wish to include:
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The setup for this lab consisted of 4 ramps and 2 balls. Each ramp was 30cm long and the balls were identical. The left ramp was horizontal and held one of the balls which was released down a very minor slope connected to the beginning of the ramp. The ramp with the extremely small slope was used to give the ball an initial velocity. We assumed that this horizontal ramp had 0 acceleration even though there was obviously friction. The right ramp was also horizontal and next to the left ramp, but it had a ramp connected to it that had a gradual, but significant slope created by propping the ramp up with 1 domino. The second ball was released onto the ramp when the ball that was first released was 10cm from where it came in contact with the left horizontal ramp. The 10 centimeter mark was indicated with a domino. Timing began when the left ball reached the 10cm mark and the right ball was released. Below is the data we recorded over 7 trials.
The data is listed in the following order: Trial Number, ‘dt for them to be even(seconds, recorded with a stopwatch), ‘ds from the beginning of the horizontal ramp that they became even (cm).
1, 1.75, 21.2
2, 3, 22.5
3, 1.7, 25
4, 2.25, 23.1
5, 2.35, 23.5
6, 2.5, 22
7, 2.25, 23
The data seems fairly consistent with what I would expect to be the case. There were several large irregularities in the data, but that is easily attributed to human error. The error occurred due to not being able to trigger the stop watch perfectly to begin or end, and that the means of marking where they crossed could have easily been a centimeter off.
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Explain how you positioned the ball representing the truck, the ball representing the car, and how you timed the release of each.
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The “truck” was released down a ramp with a very small slope as to give it a small initial velocity, and the timer was triggered when this ball reached the 10cm mark. Once the truck traveled 10cm, the “car” was released and time was stopped when it caught up.
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I believe it was the car that had the initial velocity, with the truck pulling out from rest.
However your setup should also give good results on an equivalent question, so this might not be a problem.
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According to your data what was the velocity of the ball representing the car at the instant it passed the position of the ball representing the truck?
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18.18cm/sec
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According to your data what was the acceleration of the ball representing the truck?
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7.9cm/sec^2
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According to your observations, what were the positions of the two balls when their velocities matched?
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I never observed this, but rather just calculated it.
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I believe you were supposed to eyeball that, for comparison with your calculations.
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According to your previously calculated accelerations and velocities, what were the positions of the two balls when their velocities matched?
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14.9cm for the “truck”, 7.2cm for the “car”
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You're going to need to show you analysis.
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According to your observations, at what position did the ball representing the truck overtake the ball representing the car?
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Between 21.2cm and 23.5cm
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According to your previously calculated velocities and accelerations, at what position should the ball representing the truck overtake the ball representing the car?
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22.89cm
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What I wrote down for this lab and how the numbers appear to be doesn’t really feel right. I may have drawn the system wrong when we did this in class.
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It looks like you set the system up differently, but I believe that gives you an equivalent problem, so your data will probably be OK.
However you need to document how you calculated your results from your data. You've asserted results, but you haven't explained how they were obtained.
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