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12/2/2009

Class C1, Team 3 Justin Grundt

Thomas Frederick Chris Holmes

EF 151

FINAL

PROJECT THE FINGER BREAKER

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Abstract

For the Engineering Fundamentals 151 final project, our group was given the task

of designing and constructing an original Rube Goldberg device which was

required to meet various criteria. A Rube Goldberg machine is an intentional,

excessively engineered apparatus that performs an extremely simple task in a

very complex fashion, usually including a chain reaction. Our Rube Goldberg

device incorporates numerous physics concepts (using mouse traps, a Newton’s

Cradle, a funnel with tubing, and gravity powered ramps) in a particularly

inefficient manner to simply display a University of Tennessee banner via a

novelty “bang” gun.

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Introduction

As the primary objectives, our Rube Goldberg device had to perform

independently and display a UT banner, in addition to its capability of being

initiated by another group's project, as well as triggering another device. In

accordance with the objectives, a lengthy list of additional requirements was

specified:

Device must fit within a 0.5m x 0.5m x 0.8 m box

One minute set up time

Five different steps

Must operate without interaction after initialization

The operating time must not exceed two minutes

Device must include examples of at least 4 out of the following concepts:

o Projectile motion

o Conservation of translational energy

o Conservation of rotational energy

o Conservation of linear momentum (collision)

o Conservation of angular momentum

o Torque (rotational motion)

o Center of mass (balancing an object)

A budget of $20

Must be operated in a safe, clean, and non-destructive manner

Design Process

With all the requirements stated and understood an original design was planned and sketched (See Appendix A). Each team member was assigned different smaller sections of the device to purchase and assemble initially. After all the supplies were obtained, the team collaborated to discuss and agree upon a base design for construction. Peg board was chosen as the backdrop and primary material for the device, enabling the team to build the machine in steps. By utilizing the peg board, the base of the device could be constructed first and individual components would later be attached to pegs, allowing the team to adjust certain aspects of the entire system. A few ideas were discarded during the meeting, such as a complicated pulley system that would have required extreme, if not unattainable, precision for repeated success, as well as a number of balanced levers which took up far too much space than originally anticipated.

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Device Construction and Description

Using a 0.8m x 0.5m piece of plywood as the foundation, two vertically stacked 0.7m x 0.5m sections of peg board where attached together using nuts, bolts, and a small board capable of being quickly removed thus adhering to the dimension requirements. A large spring arm was constructed using scrap wood and a mouse trap spring which was used to project a marble in the air into a funnel attached to plastic electrical tubing. Three similar wooden tracks were constructed, each equipped with switches that were designed to release an object below it. A Newton’s Cradle was also designed using PVC pipe and fittings, five golf balls, and fishing line to activate a mouse trap. After individual components were constructed, each section was attached to the peg board in a calculated manner so as to achieve the desired results and to complete the construction process of the machine. The spring arm is attached to the top left of the device and is released by a small wooden dowel that is removed by a mouse trap placed on the floor. A marble is projected by the spring arm into an accurately placed funnel. The marble travels down the funnel and into a spiraled section of plastic tubing. The tubing exits the marble on the first wooden track. As the marble travels down the track, it activates a wooden switch and releases two separate marbles down the track below. The two marbles trigger the second switch, discharging a golf ball, allowing it to roll down the third track. When the golf ball sets off the final switch, the first ball of the Newton’s Cradle is freed, causing a collision between all five balls and swinging the last golf ball against the activation switch of a set mouse trap. A piece of fishing line is attached to the mouse trap lever and to the trigger of the novelty “bang” gun. When the mouse trap snaps, the fishing line pulls the trigger of the gun and displays the UT banner.

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Analysis

For a complete and accurate analysis with appropriate and reasonable

assumptions see Appendix B.

Bill of Materials

ITEM QUANTITY PRICE

Funnel 1 $0.99 Hardware (nuts, bolts, etc.) N/A $0.99 Mouse Traps 4 $1.97 Novelty “Bang” Gun 1 $3.68 Peg Board 1 $3.78 Pegs 20 $0.99 Plastic Tubing 1 $1.99 PVC (pipe and fittings) N/A $3.12 Scrap Wood N/A $2.48 TOTAL $19.99

Results of Testing

For complete results from testing, including critique of device performance see

Appendix B.

Conclusions

The Rube Goldberg project was an interesting way to physically display the

knowledge gained throughout the semester. During the project, our team was

challenged with numerous issues such as the device triggering too early, the

precision required during the construction phase, and arranging time for our team

to meet. Although with perseverance, creativity, and constant correspondence,

our device performed flawlessly during the project demonstrations. Working

together as a team allowed each member an alternate perspective to problem

solving and opened up a door to a higher sense of ingenuity.

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References

Engineering Fundamentals: Rube Goldberg Device. http://ef.engr.utk.edu/ef151-2009-08/tm/final-project.php

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Appendix A

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Appendix B

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