|PH111L - Physics I Lab|
Fall Term 2012
Instructor: Galen C. Duree Jr., PhD
Office: Room DL102 Phone: 872-6025 Box: 182
Office Hours: 9:00 AM - 10:30 AM M T F & 4:20 PM - 5:30 PM M T Th F
The last experiments for the term, entitled "Conservation of Linear Momentum", a description of which can be found in the lab manual beginning on page 3-22 were conducted last week. The lab reports for these experiments are due in the green bin outside my office by 5:30 PM on Friday, November 9, 2012.
For this experiment, the purpose is to determine if linear momentum was conserved for three different collisions. Remember to do all of the curve fits in Logger Pro. Use only the position vs. time graphs, not the velocity vs. time graphs for your calculations. Include, at a minimum, three graphs: one levelness test (placed in the Analysis section), one sample data graph with NO curve fits on it showing both carts (placed in the Procedure section), and one sample graph showing at least one curve fit on each cart (placed in the Analysis section). Do NOT average all of the trials together because they are not the same. The uncertainty in the mass should be estimated and the uncertainty in the velocity should be determined by Logger Pro as the uncertainty of the slopes of your line fits. Remember to propagate the uncertainties through all of your calculations for the momentum before the collision and after. If the two values overlap within experimental uncertainty, then momentum was conserved. If they do not overlap, then momentum was not conserved. In the analysis section, be sure that you list explicitly the values you obtained from each data file. You do not need to show how you got each one, but you must list all of the values that you used.
The coefficient of restitution and percentage change, while instructive are NOT required, they are optional for you. However, choose one trial and determine if kinetic energy was conserved or not. Compute the total kinetic energy before the collision (with uncertainty!) and compare it to the total kinetic energy after the collision. If they are the same within uncertainty, then kinetic energy was conserved and you had an elastic collision. If not, then you had an inelastic collision.
Lab Report Format
A complete lab report must have the following sections:
Do not forget to update your Table of Contents and to number the pages in your lab notebook!
The first page of your report must have a title, the name of the P.I. (explicitly indicate who was the P.I.), the name of the lab assistant, and the date that the report was turned in (not the date that you performed the experiment!).
*Abstract - a BRIEF description of what you were investigating, how you conducted the experiment and your conclusions based on your experience. The abstract should not be a discussion of what you are going to do in the lab. The abstract cannot be written before you have analyzed your data. In the lab notebook, skip a page or two so that you can write this in at the beginning of the report after you have analyzed your data.
Introduction - a discussion about any details that you think would help someone perform the experiment. This should include a discussion about the model or the method selected for performing the tests. If you use models (equations) in your analysis, list the models in this section and describe what each of the variables represent. Do NOT include formulas for calculating averages and standard deviations.
**Procedure - a detailed description of what you did in the lab. At the beginning of this section, place the date and the time that you began the experiment. This section must include a schematic, detailing how things were connected, where appropriate. The raw data must appear in this section immediately following the description about how the data was taken. A person must be able to read your procedure section and be able to duplicate your results without having the lab manual present. Do not do any calculations in this section, just record how you performed the experiments and record the raw data. If the data is taken by computer, you must specify the path and filename where the data is stored. This information must be listed in this section right after the description of how the data was taken. Do not simply list all of the files generated at the end of the section.
This section be signed by the instructor before you leave the lab. If you turn in a report without the signature, it will not be accepted!
Analysis - a sample of the calculations made in the lab. This section should include a sample of the error calculations and propagation of errors used in your analysis. The final data that you are analyzing to generate conclusions, the values with appropriate uncertainties, must be shown in this section. The actual calculations for each one does not have to be included, as long as you show an example for one, but you may include them all if you wish. The calculations may be done by the computer, but include printouts of the worksheet in your lab book. Any graphs or printouts that are placed in your notebook must occupy one whole page and be trimmed to fit within the page and not hang outside of the notebook.
*Conclusion - this section must have a conclusion that is based on your experiments and analysis. If your conclusions do not following logically from your analysis, your grade will be deducted significantly. This section must also contain a brief description of significant factors that you think affected your data, in particular, the uncertainties in your data (factors that contributed to the error in your experiment). A good thing to keep in mind is to think of this report as a report you are submitting as part of your job responsibilities. If you do not think your boss would accept what you have to say, it is a safe bet that I will not like it either.
The asterisks indicate the sections that I will pay closest attention to.
Modified November 09, 2012 by Galen C. Duree Jr.