Scott Wherry
Daniel Triplett
Devin Adams
Jonathan Brickey
Rube-Goldberg Project Report
Overview:
The Rube-Goldberg device we have constructed is intended to flip a light switch and turn on a light. This can be done by placing a foosball on the top of a ramp which rolls through a tube of PVC pipe and then strikes a domino. The row of dominos then falls over and the last domino sets a golf ball on the top of a ramp into motion. This golf ball then rolls down the ramp and land inside of a cut out twenty ounce bottle. The bottle, with the added weight of the ball, then falls off the end of the table and flips the light switch via the string tied to each; and the light turns on.
Design Process:
The design process for this project was fairly simple. We all submitted different ideas of what we wanted to do, and then combined many of these ideas into one project. Each person gave different input, such as: using domino’s, dropping the ball from a height, using electricity somewhere within the project, and just the overall setup of the project. As a whole, the process was very smooth since all group members were open to ideas and changes. The main criteria we used in creating this project was did it comply with the rules given. We have multiple energy changes within the project, and we also complied with the rest of the rules given. The other criteria was is the project fun and simple to build, both of which we meet.
We discarded a few ideas. At first we thought the dominos would hit a lime in a Coke, but decided this was a little easy, and didn’t really make since. We also decided not to use a long domino run, but rather a fairly short one, so that way there is less room for error. As a whole we tried to incorporate everyone’s ideas, and apply then to the project.
Description of Project:
Our Rube-Goldberg device consisted of four main processes. The first of these processes consisted of an inclined trough leading to a PVC sink trap that forced the ball onto the table from a position above the table. The second phase was a series of dominoes placed in an “s” shape so that the energy would be transferred to the next stage. The third stage took the energy transferred from the falling dominoes to a ramp in which a golf ball was positioned so that the falling dominoes would contact the golf ball, forcing the golf ball down the ramp. The final stage consists of the golf ball being guided into a twenty ounce soda bottle that has been cut off approximately half way from the bottom. When the golf ball roles into the soda bottle the force of the golf ball would knock the soda bottle off of the table. The soda bottle is attached via a string to a light switch which would be pulled by the weight of the ball and soda bottle into the on position. This would in turn complete the circuit, which consisted of a nine volt battery, a marker light, and the light switch. The completed circuit would cause the marker light to turn on.
Picture:
Detailed Analysis of Energy Conversions and Calculations:
Given:
Mass (orange ball) = .005 kg
Mass (golf ball) = .01 kg
Mass (dominoes) = .002 kg
Height of First Ramp = .833 feet
Height of Second Ramp = .0833 feet
Part 1:
The orange ball rolls down the ramp, into the pipe, and out onto the platform.
Calculations: Finding the velocity as the ball exits the pipe. The point where the ball exits the pipe is set as the datum.
Conservation of Energy
mgho = .5mv2 (masses cancel out)
(32.2)(.833) = .5v2
v = 7.32 ft/sec
Part 2:
The orange ball collides with the first domino as it exits the pipe.
Calculations: Finding the velocity of the domino upon impact of the orange ball, traveling with a velocity of 5.18 ft/sec.
Conservation of Momentum
m1v1 = m2v2’
(.005)(7.32) = (.002)v2’
v = 18.3 ft/sec
Part 3:
The dominoes complete their chain reaction-rally and collide with the golf ball place on the top of the second, smaller ramp.
Assumptions: The dominoes maintain a constant velocity throughout their rally.
Calculations: Find the velocity of the golf ball following its collision with the domino.
Conservation of Momentum
m1v1 = m2v2’
(.002)(18.3) = (.01)v2’
v = 3.66 ft/sec
Part 4:
The golf ball rolls down the ramp into the bottle.
Calculations: Finding the velocity of the golf ball as it drops into the cup, in turn, flipping the switch.
Conservation of Energy
mgho + .5mvo2 = .5mvf2 (masses cancel out)
(32.2)(.0833) + .5(3.66)2 = .5vf2
vf = .895 ft/sec
Bill of Materials:
Item / Cost ($)Dominos / 3.96
Shims / 1.98
Duct Tape / 1.00
PVC Piping / 2.79
Ping Pong Balls / 1.00
2x2 Plywood / 3.25
Yellow Light / 2.48
Light Switch / 2.50
Battery / 0.99
Total / 19.95
Conclusion:
The project is success in that it performs the function we had in mind. The ball drops from its initial height, hits the dominoes, which in turn hits a ball that will cause the lighting of a bulb.
What we learned was that these projects require proper planning, and that you cannot just leap right into it. I think maybe a better outline/sketch would have been more beneficial and could have saved more time. This knowledge can help in future courses and projects.
Once we got everything down, we really had only a few problems. The only real problem was that at first the ball did not drop the bottle off the table, which in turn did
not light the bulb. This was fixed by creating an easier resting point for the bottle so when the ball landed in the bottle, it dropped with greater ease. And the only other problem was
the setting up of the dominoes. The dominoes can fall easily, so when setting up we had to be very careful.
The only thing we would have done differently was have a better “pre-game” plan for the project. At first we kind of jumped into it, but then realized we needed to write our ideas down. Other than that, the overall project was a success.
References:
We would like to reference Honda. We watched their Super Bowl Rube-Goldberg commercial to get a good idea of what a Rube-Goldberg project should demonstrate. We would also like to thank Nolan Morrell for his ideas on using dominoes within the project.