“The Revolting Blob”

Engineering Fundamentals 151

Section: B1

Team 3:

Stephen Phillips

Aaron Messer

Joe Carrier

Mitchell Davis

28 April, 2006

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Table of Contents

Table of Contents......

Executive Summary......

Description of Design Process......

Description of What We Built......

Detailed Analysis of Energy Conversions......

Bill of Materials......

Summary......

Contribution of Each Team Member......

References......

Executive Summary

Wood and PVC pipes were used to create a device witch turned on a teddy bear lamp. The process begins with a ball being launched down a tube by a spring. The ball proceeds down a ramp and collides with a pivot. The pivot turns and hits another ball. This second ball goes down another ramp, into a modified funnel, and then onto another ramp witch leads to the lamp's switch. The ball hits the switch, turning the lamp on. Besides the wood, the other materials needed are nails, drywall screws, a spring, a PVC cap, tubing, a lamp, and a light switch.

Description of Design Process

After discussing it between us, our team decided to build a device witch would turn on a lamp. One of our team members works at a hardware store and so we decided to use wood and PVC pipe as our primary construction material. The original design of the device included dominoes were the first ball ramp was built. However, the final structure of the device was not stable enough; every time we fired our ball all the dominoes fell over. So, we modified the design so that a ball would cause the pivot to hit the golf ball. Also the original design included two switches, one to turn the lamp on and the other to turn it off again. This idea was abandoned after the team decided that it would be impractical given the price limit and time constraints. We also tried to keep the device fairly simple to ensure consistence while still allowing it to have plenty of energy transfers.

Description of What We Built

The first step is the launching mechanism; a PVC pipe with a removable cap and a spring inside, followed by the tubing.


Then there is the ramp leading to the pivot witch hits the Golf Ball.

Next comes the sloping ramp followed by the funnel.

Finally, came the last ramp and the switch witch turned on the lamp.

Detailed Analysis of Energy Conversions

Measurements:

Maxheight of Ball 1: 54”

Heightpivot: 43”

Heightswitch: 4”

Massballs: .0459 kg or 0.00314514905 slugs

Kspring: 1 lbf/ft

Assume that the spring is compressed 1” before the device is started.

V0 of ball1 just after the device is started:

PEspring = KE

.5kx2 = .5mv2

.5(1lbf/ft)(.08ft)2 = .5(.00315slugs)(v0)2

v0 = ((.5*1lbf/f*(.08ft)2)/(.5*.00315slugs)) = 1.425 ft/sec

V1 of ball1 just before contact with the pivot:

KE + PEg = KE

.5(1.425 ft/sec)2 + 32.2 ft/sec2(.92 ft) = .5(v12)

v1 = (2(.5(1.425 ft/sec)2 + 32.2 ft/sec2(.92 ft))) = 7.83 ft/sec

Assume that the pivot is perfectly efficient and no energy is lost

v0 of ball2 = v1 = 7.83 ft/sec

V1 of ball2 on impact with the switch:

KE + PEg = KE

.5(7.83 ft/sec)2 + 32.2 ft/sec2(3.25 ft) = .5(v12)

v1 = (2(.5(7.83 ft/sec)2 + 32.2 ft/sec2(3.25 ft))) = 16.5 ft/sec

Bill of Materials

  • The primary materials used were wood and PVC pipe. One 2x4 was purchased from Lowes costing $4.00. Also, one 2x2 and one 1x2 were purchased costing a total of $4.25. The PVC cost $1.25 per foot and three feet were purchased.
  • A piece of particleboard was also used. It was free because one of the team members got it from home.
  • Tubing another of the materials used. It was $2.00 per foot and three feet were purchased
  • The balls were also free; one of our team members plays golf and so we just borrowed a couple.
  • One $1.50 spring was used along with a $0.50 PVC cap.
  • The lamp was $3.00 at Goodwill
  • Also, we purchased a $2.00 light switch at Lowes.

Summary

We were successful over all because we produced a creative device to perform the simple task of turning on a lamp with a reproducible, accurate outcome. Also, we accomplished the objectives given. We solved an open-ended question while working in a team. We communicated in different ways, through a written report, presentation, and web pages. We also got to have a little fun creating our device.

We learned that teamwork is important; you can’t always do everything on your own. You must have other people’s ideas and inputs to make the most desirable device. The things we have been learning all year were driven home by having to represent them in concrete form. We learned how to economically build our device. Luckily for us, one of our team member’s jobs allowed for discounted and free supplies.

One problem we did encounter was that most people’s schedules didn’t line up very well. Also, we ran into a couple of design issues witch had to be rethought out and led to redesigning certain sections of our Rube-Goldberg device.

We did a pretty good job on our project. One thing we might have done a little differently could have possible been to start a little sooner on the presentation and report even though time didn’t present too much of a problem.

Contribution of Each Team Member

Everyone contributed equally to this project. Aaron Messer provided the report and some of the materials, as well as helped with the construction. Steven Phillips supplied the wood and PVC, as well as doing a considerable amount on the construction. Trey Carrier bought the teddy bear lamp and helped with the construction. Jordan put together the power point presentation and helped wire the lamp. We all helped with ideas, calculations, and attended regular team meetings.

References

We came up with most of our own ideas, making our device completely original. We did borrow our calculations from the book and class.

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