Physics 163 - Quarter 2 Projects

Momentum Conservation

The Lab Report

Momentum Conservation Project Description

About the Lab Report

Due Dates

The Project Corner


Your success in this project will be evaluated using a scoring rubric. Your understanding of physics and your ability to design, conduct, and communicate the results of an experiment is the focus of the evaluation. Your final product will be a formal lab report which communicates your purpose, background understanding, procedure and findings, and conclusions. The formal lab report is thus the critical document which reflects your success. For this reason, it is important that you understand exactly what should be included in the formal lab report and how it should be put together. Directions for each step of the process have been described in the Overview for this project. The purpose of this page is to further explain the details.


Contents and Organization:

The lab report should include all the customary sections included in a lab report. Such sections include:

These sections should be clearly titled and organized in the exact manner as shown above. The graphic at the right depicts the organizational scheme which you should have and an approximate number of pages which each section might typically have.


Description of Each Section:

  1. Title Page - includes a meaningful title for your project report and the names of the experimenters. Some students will occassionally include a colorful graphic on the page.
  2. Purpose - a paragraph in which you succinctly describe your overall study and state the goal of your investigation; the purpose should be clearly stated and to the point. Procedural steps should not be discussed in the purpose section.
  3. Procedure - a step-by-step procedure which describes what you will do and how you will do it. The procedure always ties into the purpose of the experiment; that is, the procedure describes in detail the steps which an experimenter must take in order to accomplish the stated purpose. The procedure should be so specific and clearly stated that a stranger could repeat the experiment without knowing anything about it. If an experimental investigation includes several parts (and yours does), then the procedure should have the equivalent number of parts. Each part should be appropriately labeled (e.g., Part A - Explosion Analysis, Part B - Inelastic Collision Analysis, etc.). The procedure must be accompanied by informative diagrams of the experimental set-up for each part of the investigation.
  4. Theoretical Background - exhaustively describe the physics of explosions and collisions. Include diagrams, graphs, tables and other visuals which have been discussed in class or which you found in the book or other literature. In other words, apply physics to your project by intelligently discussing the applicable physics principles. Include a discussion of Newton's laws, kinematics, impulse-momentum change, momentum conservation, and energy conservation (or non-conservation) in elastic and inelastic collisions. This is a critical part of your project and should be several pages in length. There is no minimum limit on the number of pages which must be included. Nonetheless, the actual number of pages will be revealing of your knowledge level; "the more you know, the more you'll write."
  5. Data and Calculations Section - include an organized listing of all collected and calculated data; use a row-column format for data. Use whatever format makes the data most revealing of the focus of your investigation - momentum conservation. Use more than one data table; this is especially important since the amount of data collected for any given trial is enormous. Give each table a title (e.g., "Inelastic Collision - Calculated Data" or "Inelastic Collision - After Collision Data"). For any column of calculated data, include 1 sample calculation to illustrate how the data in the given column was determined.
  6. Discussion of Results (sometimes called the Conclusions) - briefly describe the successful trials for each section of your investigation. Comment on your overall accuracy and make reference to the percent error and percent difference calculations. Identify and describe potential source of error and discuss how these sources might have impacted your results. Include a paragraph or more in which you identify and discuss any suggested changes in your procedure for data collection.


Common Errors and Pitfalls to Avoid:

There are a number of errors which are commonly made which you would be wise to avoid. Such errors include the following:

  1. Failure to write a formal lab report and the tendency to write a paper similar in style to a narrative.
  2. Failure to label the sections of the lab report such that it is not clear whether a given part of it is reporting on the procedure, the data or the conclusions.
  3. Tendency to place procedural statements in the purpose (e.g., "we will then measure the photogate time at point A and calculate the speed, repeating the measurements three times to insure accuracy") and in the Conclusion section (e.g., "we measured the photogate time and calculated the instantaneous speed and then found the kinetic energy and total mechanical energy...").
  4. Failure to write a solid and lengthy theoretical background and tendency to merely state a short hypothesis (e.g., "we believe that momentum will be conserved."). The theory should be a lengthy section in which you demonstrate that you know how a wealth of physics applies to your investigation.
  5. Failure to include a step-by-step detailed procedure which would provide sufficient direction for anyone to follow. The steps should be sequential and numbered and include enough detail for a person who is unfamiliar with the equipment to conduct the same study.
  6. Tendency to use the first person in the procedure section - "I then placed selected the rectangle tool. Then I drew a box by dragging on the screen. I then ...".
  7. Tendency to merely restate your measured data in the Discussion of Results section (e.g., "we measured the photogate times to be 0.0125 s and the speed to be 0.451 m/s and we measured the time to be 0.0251 s when the height was 0.225 m/s").
  8. Tendency to make very general conclusions which (while perhaps true) have nothing to do with the idea behind the lab investigation (e.g., "This project was fun and we learned alot. We hope that we can do more projects like this.").

In general, all of these errors and pitfalls are usually the result of either not following project guidelines or rushing the project together at the last minute (which subsequently leads to a tendency to not follow directions). Thus, give yourself plenty of time and take the time and effort needed to be acquainted with the guidelines described on these Internet pages.



Exemplary (for the most part) projects are included online at The Refrigerator; a quick glance at these pages is highly recommended prior to the completion of your project. Such examples are not included for you to mimic, but rather as helpful illustrations of what your own end product might look like. Students should be cautioned that project guidelines change through the years and thus the online exemplars should not be considered as the definitive word concerning what should be included in the final lab report. The definitive word are the guidelines which are included on these Internet pages.

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Momentum Conservation Description
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This page last updated on 1/21/99.