Physics 163 - Quarter 2 Projects

Momentum Conservation

Project Description

Momentum Conservation Project Description

About the Lab Report

Due Dates

The Project Corner


This project is designed for students to explore the momentum of a system before and after an explosion and various collisions. Students will design experiments to investigate whether momentum is conserved in such situations. Using rolling carts, photogate timers and/or sonic motion detectors, students will create the laboratory environment which would foster a thorough study of momentum.



1. Obtain a super track, two "friction-free" rolling carts, additional mass bars, bumpers, and timers. Set up the track system and check to be sure it is level so as no other forces will be applying impulses into the system.

2. Select and become familiar with a method of timing - photogate timers or sonic motion detectors. If using a photogate timer, become familiar with the different settings, the use of the memory function, and the use of a flag to determine the cart speed. If using the sonic ranger and the ULI software, conduct some practice runs to help familiarize yourself with this previously used equipment.

3. Three different experiments will take place in this study: an Explosion; an Inelastic Collision in which cars stick together after the collision (utilizes velcro strips); and an Elastic Collision in which the cars completely bounce off of each other after the collision (utilizes magnets). Brainstorm and test reliable procedures for collecting data for each of these three experiments. Consider where the timing systems (photogates or sonic rangers) should be located in order to determine before- and after- momentum of the individual carts. Decide whether cart A and/or cart B will be at rest or in motion; and if in motion, decide which way the cart will be moving. Make careful and detailed notes and diagrams which will allow you to draft a step-by-step procedure for each of these three experiments.

4. Submit a word-processed proposal for your project. The proposal should contain a purpose for your experiment, a step-by-step description of the procedure and the experimental set up (including diagrams) and a brief discussion of the physics theory behind the experiment.

5. Many practice trials will need to be performed for each of the three experiments so as to assure a consistent explosion or collision. Practice first without the timers and then practice with the timers. Make any necessary modifications to your proposed procedure. When confident of your technique, begin the experiment trials and record your data in a data table. Since the explosions and collisions take so little time to create, be sure to have at least 10 trials for each experiment. Remember that momentum is the ulitmate quantity to calculate, so gather the information which will allow that calculation to be made for each trial.

6.Organize your data into neat tables before you write up your report. Consider the best means of presenting the data; the best means is the means which hilites the momentum conservation of the system. This may mean that you will need more than one data table for each of the three experiments. Preparing your tables now will allow for easy understading throughout the experiment which will take place over weeks. A word-processed data table will be submitted prior to the final lab report.

7. Develop a theoretical background for your project. 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."

8. Carefully diagram the working space you used for your investigation. Plan your computer-drawn pictures for illustration purposes. Your pictures should show the difference between the different types of collisions and explosions.

9. Repeat steps 5 and 6 for two cars which have different masses. Do this by adding a mass bar to one of the cars. Repeat the investigations in the same style to determine momentum conservation for these unequally-massed cars.

10. Submit a written lab report which includes the following sections - Purpose (step 4), Procedure (step 4), Diagrams (step 8), Theoretical Background (step 7), Data/Calculations Section (step 6), and Discussion of Results (in which you briefly discuss the both successful and unsuccessful trials, percent differences and percent errors, and sources of error). The report should be in the form of a scientific lab report; this is not a narrative for an English class. Further information available.


Due Dates:

The following due dates have been tentatively assigned for the completion of your project. Meeting these deadlines will insure that you receive useful and timely feedback from your instructor and that you meet the final deadline without the necessity of a "last-minute rush."

Selection of Project

Friday, 12/4

Acquisition of Materials (steps 1 and 2), Trial Runs Complete (step 3), and Word-Processed Proposal Due (step 4)

Friday, 12/11

Submission of Data Table (step 6)

Wednesday, 12/16

Submission of Theoretical Background(step 7)

Friday, 12/18 (no later; no excuses)

Submission of Final Lab Report (step 10)

Thursday, 1/6


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This page last updated on 1/21/99.