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Unformatted text preview: u cannot confirm your prediction, then estimate which are the most important. Conclusion Consider your conclusion the wrapping paper and bow tie of your report. At this point, you should already have said most of the important things, but this is where you collect them in one place. Remind your audience what you did, what your result was, and how it compares to your prediction. Tell her what it means. Leave her with a sense of closure. Quote your result from the Analysis section and interpret it in the context of the hypothetical scenario from the Introduction. If you determined that there were any major shortcomings in your experiment, you might also propose future work to overcome them. If the Introduction was your attempt to justify your past funding, then the Conclusion is your attempt to justify your future funding. What Now? Read the sample reports included in this manual. There are two; one is an example of these instructions implemented well, and the other is an example of these instructions implemented poorly. Then, talk to your TA. He can answer any remaining questions that you might have. There is a lot of information here, so using it and actually writing your lab report might seem a little overwhelming. A good technique for getting started is this: complete your analysis and answer your question before you ever sit down to write your report. At that point, the hard part of the writing should be done: you already know what the question was, what yo=0 and that the Vy graph would be a linear line with Vy(z)=-10z. Next, we fit the functions to the data points for the velocity graphs. We got the predictions exactly right. We then printed our data for the street hockey ball and closed MotionLab. We repeated this process for a baseball with a mass of 143.0g. It was mostly the same, with some exceptions. The y(z) fit was y(z)=-4.85zˆ2 instead of y(z)=-5zˆ2. The Vy(z) prediction was Vy(z)=-9.7z instead of Vy(z)=-10z. These were also exactly right, so the Vy(z) fit was the same. At the end of the lab, everybody put their data on the board so we would have enough to do the analysis. We copied it down. Then we were finished, so we started the next experiment. Data Ball 1 mass: 12.9+/-0.05g x prediction: x=0z x fit: x=0z y prediction: y=-4.9zˆ2 y fit: y=-4.8zˆ2 Vx prediction: Vx=0z Vx fit: Vx=0z Vy prediction: Vy=-9.6z Vy fit: Vy=-9.6z Ball 2 mass: 48.8+/-0.05g x prediction: x=0z x fit: x=0z y prediction: y=-4.9zˆ2 y fit: y=-5.1zˆ2 Vx prediction: Vx=0z Vx fit: Vx=0z Vy prediction: Vy=-10.2z Vy fit: Vy=-10.2z Ball 3 mass: 55.8+/-0.05g x prediction: x=0z x fit: x=0z y prediction: y=-4.9zˆ2 y fit: y=-4.9zˆ2 Vx prediction: Vx=0z Vx fit: Vx=0z Vy prediction: Vy=-9.8z Vy fit: Vy=-9.8z Ball 4 mass: 56.7+/-0.05g x prediction: x=0z x fit: x=0z y prediction: y=-4.9zˆ2 y fit: y=-4.95zˆ2 Vx prediction: Vx=0z Vx fit: Vx=0z Vy prediction: Vy=-9.9z Vy fit: Vy=-9.9z Ball 5 mass: 57.7+/-0.05g x prediction: x=0z x fit: x=0z y prediction: y=-4.9zˆ2 y fit: y=-5.0zˆ2 Vx prediction: Vx=0z Vx fit: Vx=0z Vy prediction: Vy=-10.0z Vy fit: Vy=-10.0z Ball 6 mass: 143.0+/-0.05g x prediction: x=0z x fit: x=0z y prediction: y=-4.9zˆ2 y fit: y=-4.85zˆ2 Vx prediction: Vx=0z Vx fit: Vx=0z Vy prediction: Vy=-9.7z Vy fit: Vy=-9.7z 269 APPENDIX: SAMPLE LAB REPORT Ball 7 mass: 147.6+/-0.05g x prediction: x=0z x fit: x=0z y prediction: y=-4.9zˆ2 y fit: y=-4.8zˆ2 Vx prediction: Vx=0z Vx fit: Vx=0z Vy prediction: Vy=-9.6z Vy fit: Vy=-9.7z Analysis We can calculate the acceleration from the MotionLab fit functions. To do this, we use the formula x = x0+v0t+1/2atˆ2. Then a is just 2 times the coefficient of zˆ2 in the position fits. This gives us Ball 1: a=-9.6 Ball 2: a=-10.2 Ball 3: a=-9.8 Ball 4: a=-9.9 Ball 5: a=-10.0 Ball 6: a=-9.7 Ball 7: a=-9.6 The acceleration can also be calculated using the formula v=v0+at. Then a is just the coefficient of z in the velocity fits. This gives us Ball 1: a=-9.6 Ball 2: a=-10.2 Ball 3: a=-9.8 Ball 4: a=-9.9 Ball 5: a=-10.0 Ball 6: a=-9.7 Ball 7: a=-9.7 We know that the acceleration due to gravity is -9.8m/sˆ2, so we need to compare the measured values of the acceleration to this number. Looking at the data from the fits, we can see that they are all close to -9.8m/sˆ2, so the error in this lab must not be significant. Ball 3 actually had 0 error. We need to analyze the sources of error in the lab to interpret our result. One is human error, which can never be totally eliminated. Another error is the error in MotionLab. This is obvious because the data points don’t lie right on the fit, but are spread out around it. Another error is that the mass balance could only weigh the masses to +/-0.05g, as shown in the data section. There was error in the fisheye effect of the camera lens. There was air resistance, but we set that to 0, so it is not important. Conclusion We predicted that a would be -9.8m/sˆ2, and we measured seven values of a very close to this. None was off by more than 0.4m/sˆ2, and one was exactly right. The errors are therefore not significant to our result. We can say that the canisters fall at 9.8m/sˆ2. This experiment was definitely a success. 270...
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This document was uploaded on 02/23/2014 for the course MANAGMENT 2201 at University of Michigan.

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