Mousetrap Vehicle Calculations for Design Excellence
There are two main stages of travel for mousetrap vehicles (MTV). The first is the
powered stage and the second is the coasting stage. There is a possible third stage that should be avoided by careful routing of the string – the breaking stage – since this will reduce distance but with no positive offsetting effect.
Since the powered stage accounts for the majority of the distance and the time used, it is wise to optimize this phase. To begin the design, we’ll ignore length and weigh
considerations (but they should be evaluated as part of the final MTV design). Once the
initial design is complete, trade-offs and improvements can be made.
To calculate distance under power for an existing MTV design, you determine how many
times the wheel will rotate and multiply that by its circumference to get total distance. If the vehicle does not perform as anticipated then you can look for losses due to slippage and other factors, or perhaps a math error. Include units in all calculations to avoid use of conflicting units (dimensional analysis).
https://sites.google.com/site/seminolesecme/curriculum-of-the-consortium/Mousetrap%20Vehicle%20Calculations%20for%20Design%20Excellence.pdf
based on a 2011 SECME Saturday Design Seminar originally presented at Pine Jog Elementary School.
Showing posts with label Technical Report. Show all posts
Showing posts with label Technical Report. Show all posts
Monday, October 8, 2012
Thursday, January 26, 2012
Technical Report for Balsawood Bridge
EDITOR'S NOTE: For a change, the comments are being left ON. I welcome and would appreciate your thoughts -- this technical report has not been scored yet, so it will be interesting for your feedback to compare & contrast with the judges. Just keep it constructive, if you'll pardon the pun! :D
Design Philosophy and Construction Procedure
As stated in the introduction, we used the Warren Truss, with slight alterations, for our design. Even before we began our research, our design was based on common sense, intuition and prior experience. With force being applied to the truss we knew that we had to build a design where it was distributed and transferred to the supports with as little stress as possible to the bridge. The top of the bridge is where the compression is located when force is applied, and if not handled appropriately the bridge will snap inwards; while if there’s too much tension, on the bottom of the bridge, it will slide apart and buckle. Knowing this, we decided to use equilateral and isosceles triangles, with 60-60-60 and 90-45-45 degrees to dissipate the force being placed on the bridge by both gravity and the machine.
The force of gravity (weight) is equal to the product of the mass of the bridge times the acceleration due to gravity, in accord with Newton’s 2nd law of motion (Fnet=ma). According to the 3rd law of motion, the bridge tester will exert a normal force back on the bridge that is equal in force to weight but opposite in direction. The bridge testing machine will apply force equal to the product of pressure times area (P = F/A or F = PA). The pressure will also be equal to the work done by the tester over the volume of the bridge, where work is the product of force times distance time cosine of the angle relative to the direction of motion (W=Fd cos θ), and volume is area times depth (V=Ad). So (P = W/V = Fd cos θ/Ad). As the crusher does it’s work, the force of the load is transmitted along our beams. That stress will cause deformation from shearing and strain of extension and compression as previously stated once we pass the point of elasticity (Young’s modulus).
Our first design used the triangular method, with two sides at an angle connected by a roadway, but on our bottom beam we had vertical pieces of would which we soon realized would snap under the stress of compression and used too much wood. Our second design consisted of three major triangles with one smaller one inside of the middle triangle all at 60 degrees. The change leading to our third and last design was adding another beam for more support and changing our corresponding triangles to equal angles with our major ones being isosceles or equilateral.
Although it may’ve been better to stand the whole bridge at an angle, we have it at 90 degrees, with space between, hopefully to displace the force with greater efficacy. The goal of our BBB bridge is to attain the highest amount of efficiency possible with the given materials. Efficiency is measured by taking the ratio of the mass of the bridge itself compared to the mass that the bridge can hold. That number is then multiplied by 100 to discover the percent of efficiency. A highly efficient bridge would have its own weight at minimum and the amount of weight it could hold, at maximum.
Bridge Construction
After the team agreed to on final design, we gathered the needed materials necessary to construct the bridge: one-quarter by one-quarter inch (¼” x ¼”) balsa wood thirty-six inches long (36”) provided for us by our SECME coordinator, and we began to cut the pieces. Beam lengths were as determined by competition rules (EX: no member shorter than two inches (2”)). Angles were joined at 60-60-60 and 90-45-45 degrees. Pieces were adhered together with cyanoacrylate glue. We allowed the glue time to dry with each piece so it would not compromise the structure of the bridge.
Top view: roadway span: 45 cm in length by 4.5 cm in width
End view: roadway span: 4.5 cm in width by 1.3 cm in depth, attached to truss 18 cm in height by 4.5 cm in width
Side view: total bridge height of 18 cm, with central truss height clearance of 2 cm and width clearance of 45 cm
Conclusion
As foreboding as this task was in the beginning, we predict that our bridge will do pretty well. With an understanding of how the force of gravity and the testing machine cause tension and compression on the bridge, we presume to have designed and built a bridge to withstand the stress, strain and sheering being placed on it. However, if we were to voice concern over possible failure areas it would be at the intersection of our 45/60 degree angles. Seeing as how the force is being directed towards the center of the bridge there’s a fear that tension will occur resulting in movement of supporting beams.
Selected Bibliography
- NOVA Online | Super Bridge. (n.d.). PBS. Retrieved February 22, 2010, from http://www.pbs.org/wgbh/nova/
- "BrainPOP | Technology | Learn about Bridges." BrainPOP - Animated Educational Site for Kids - Science, Social Studies, English, Math, Arts. Web. 18 Jan. 2012. http://www.brainpop.com/technology/scienceandindustry/bridges/.
Design Philosophy and Construction Procedure
As stated in the introduction, we used the Warren Truss, with slight alterations, for our design. Even before we began our research, our design was based on common sense, intuition and prior experience. With force being applied to the truss we knew that we had to build a design where it was distributed and transferred to the supports with as little stress as possible to the bridge. The top of the bridge is where the compression is located when force is applied, and if not handled appropriately the bridge will snap inwards; while if there’s too much tension, on the bottom of the bridge, it will slide apart and buckle. Knowing this, we decided to use equilateral and isosceles triangles, with 60-60-60 and 90-45-45 degrees to dissipate the force being placed on the bridge by both gravity and the machine.
The force of gravity (weight) is equal to the product of the mass of the bridge times the acceleration due to gravity, in accord with Newton’s 2nd law of motion (Fnet=ma). According to the 3rd law of motion, the bridge tester will exert a normal force back on the bridge that is equal in force to weight but opposite in direction. The bridge testing machine will apply force equal to the product of pressure times area (P = F/A or F = PA). The pressure will also be equal to the work done by the tester over the volume of the bridge, where work is the product of force times distance time cosine of the angle relative to the direction of motion (W=Fd cos θ), and volume is area times depth (V=Ad). So (P = W/V = Fd cos θ/Ad). As the crusher does it’s work, the force of the load is transmitted along our beams. That stress will cause deformation from shearing and strain of extension and compression as previously stated once we pass the point of elasticity (Young’s modulus).
Our first design used the triangular method, with two sides at an angle connected by a roadway, but on our bottom beam we had vertical pieces of would which we soon realized would snap under the stress of compression and used too much wood. Our second design consisted of three major triangles with one smaller one inside of the middle triangle all at 60 degrees. The change leading to our third and last design was adding another beam for more support and changing our corresponding triangles to equal angles with our major ones being isosceles or equilateral.
Although it may’ve been better to stand the whole bridge at an angle, we have it at 90 degrees, with space between, hopefully to displace the force with greater efficacy. The goal of our BBB bridge is to attain the highest amount of efficiency possible with the given materials. Efficiency is measured by taking the ratio of the mass of the bridge itself compared to the mass that the bridge can hold. That number is then multiplied by 100 to discover the percent of efficiency. A highly efficient bridge would have its own weight at minimum and the amount of weight it could hold, at maximum.
Bridge Construction
After the team agreed to on final design, we gathered the needed materials necessary to construct the bridge: one-quarter by one-quarter inch (¼” x ¼”) balsa wood thirty-six inches long (36”) provided for us by our SECME coordinator, and we began to cut the pieces. Beam lengths were as determined by competition rules (EX: no member shorter than two inches (2”)). Angles were joined at 60-60-60 and 90-45-45 degrees. Pieces were adhered together with cyanoacrylate glue. We allowed the glue time to dry with each piece so it would not compromise the structure of the bridge.
Top view: roadway span: 45 cm in length by 4.5 cm in width
End view: roadway span: 4.5 cm in width by 1.3 cm in depth, attached to truss 18 cm in height by 4.5 cm in width
Side view: total bridge height of 18 cm, with central truss height clearance of 2 cm and width clearance of 45 cm
Conclusion
As foreboding as this task was in the beginning, we predict that our bridge will do pretty well. With an understanding of how the force of gravity and the testing machine cause tension and compression on the bridge, we presume to have designed and built a bridge to withstand the stress, strain and sheering being placed on it. However, if we were to voice concern over possible failure areas it would be at the intersection of our 45/60 degree angles. Seeing as how the force is being directed towards the center of the bridge there’s a fear that tension will occur resulting in movement of supporting beams.
Selected Bibliography
- NOVA Online | Super Bridge. (n.d.). PBS. Retrieved February 22, 2010, from http://www.pbs.org/wgbh/nova/
- "BrainPOP | Technology | Learn about Bridges." BrainPOP - Animated Educational Site for Kids - Science, Social Studies, English, Math, Arts. Web. 18 Jan. 2012. http://www.brainpop.com/technology/scienceandindustry/bridges/.
Tuesday, February 8, 2011
Technical Report for Mousetrap Vehicle
EDITOR'S NOTE: For a change, the comments are being left ON. I welcome and would appreciate your thoughts -- this technical report has not been scored yet, so it will be interesting for your feedback to compare & contrast with the judges. Just keep it (pardon the pun) constructive! :D
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Abstract
My team consisted of 4 freshmen in high school, we were all friends and we decided to work as a team to complete a mousetrap vehicle. The mousetrap vehicle in question is a triangular, four wheeled, balsa wood vehicle. It uses the potential energy stored in the spring of the mousetrap car to move. A string attached to the rear axle of the vehicle is also connected to the end of the straightened arm of the mousetrap. When you pull the arm back and wind the string around the axle it creates tension and potential energy. When the arm is released this energy is transformed into kinetic energy and thus the vehicle moves. This report is about how we accomplished this feat.
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Abstract
My team consisted of 4 freshmen in high school, we were all friends and we decided to work as a team to complete a mousetrap vehicle. The mousetrap vehicle in question is a triangular, four wheeled, balsa wood vehicle. It uses the potential energy stored in the spring of the mousetrap car to move. A string attached to the rear axle of the vehicle is also connected to the end of the straightened arm of the mousetrap. When you pull the arm back and wind the string around the axle it creates tension and potential energy. When the arm is released this energy is transformed into kinetic energy and thus the vehicle moves. This report is about how we accomplished this feat.
Thursday, January 6, 2011
NASA Genesis EPO - Dynamic Design: Launch and Propulsion
http://genesismission.jpl.nasa.gov/educate/scimodule/Launch_Propulsion.html
In Dynamic Design: Launch and Propulsion, students become familiar with how rockets are launched. Students will also learn how and why specific rockets are chosen for varying payloads. In this middle school module (grades 5-9), students learn about the history of rocketry and work with variables that might affect the performance of a launch vehicle.
Students work in teams to investigate one variable, in detail, by performing tests. By completing these tests they will learn the various aspects of launching a rocket. In the assessment, students engage in a competition whereby they apply what they have learned about rockets to build a launch vehicle that flies as high as possible.
Students will work in teams to learn about various aspects of launching a water rocket. Students work in expert groups to learn more about variables related to propulsion, the shape, size, number and placement of fins and the nosecone shape. Students then take the information learned in the expert groups back to their design group to design and build a water rocket that will fly as high as possible.
In Dynamic Design: Launch and Propulsion, students become familiar with how rockets are launched. Students will also learn how and why specific rockets are chosen for varying payloads. In this middle school module (grades 5-9), students learn about the history of rocketry and work with variables that might affect the performance of a launch vehicle.
Students work in teams to investigate one variable, in detail, by performing tests. By completing these tests they will learn the various aspects of launching a rocket. In the assessment, students engage in a competition whereby they apply what they have learned about rockets to build a launch vehicle that flies as high as possible.
Students will work in teams to learn about various aspects of launching a water rocket. Students work in expert groups to learn more about variables related to propulsion, the shape, size, number and placement of fins and the nosecone shape. Students then take the information learned in the expert groups back to their design group to design and build a water rocket that will fly as high as possible.
http://exploration.grc.nasa.gov/education/rocket/flteqs.htmlCiteFast: Citations for Technical Reports
CiteFast automatically will format references for your technical reports. In seconds generate bibliographies and title pages in MLA, APA and Chicago.
http://www.citefast.com
http://www.citefast.com
Tuesday, May 25, 2010
ScienceBits: Water Propelled Rocket
Professor Nir Shaviv is a member of the Racah Institute of Physics in the Hebrew University of Jerusalem. He has also launched water bottle rockets with his son, and in 2006 posted about it on his personal blog ScienceBits.
Prof. Shaviv begins with a derivation of the basic rocket equation, using conservation of impulse-momentum. Then he adds the external forces, and later continue with calculating the velocity of the ejected water. This is achieved by considering the adiabatic expansion of the gas trapped in the bottle, and the work it does to accelerate the 'exhaust'.
It's all solid physics for a liquid and gas propulsion of water and compressed air. You don't have to be a rocket scientist to follow the derivations, although you should have passed the first semester of Physics for them. And if you have, and you are also in Seminole SECME, your technical report just became significantly easier!
Prof. Shaviv begins with a derivation of the basic rocket equation, using conservation of impulse-momentum. Then he adds the external forces, and later continue with calculating the velocity of the ejected water. This is achieved by considering the adiabatic expansion of the gas trapped in the bottle, and the work it does to accelerate the 'exhaust'.
It's all solid physics for a liquid and gas propulsion of water and compressed air. You don't have to be a rocket scientist to follow the derivations, although you should have passed the first semester of Physics for them. And if you have, and you are also in Seminole SECME, your technical report just became significantly easier!
Sunday, March 7, 2010
Technical Report for Water Bottle Rocket
EDITOR'S NOTE: For a change, the comments are being left ON. I welcome and would appreciate your thoughts -- this technical report has not been scored yet, so it will be interesting for your feedback to compare & contrast with the judges. Just keep it (pardon the pun) constructive! :D
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TEAM SILVER Technical Report on Water Bottle Rocket excerpt
Introduction
In the 2009/2010 SECME competition, our mission was to construct an efficient water bottle rocket that could remain airborne for the longest period of hang time. In order to achieve this goal, we had to not only go through the process of trial and error, but also, apply our knowledge of physics. We needed to have a mastery of areas such as aerodynamics, Newton’s Laws of Motion, gravity, acceleration, air resistance, momentum, inertia and the ability to make precise and accurate calculations and plan each step accordingly. In the process of building these rockets, we enhanced our life skills, such as responsibility, hard work, teamwork, and of course, ingenuity.
Design Background
In the process of building the water bottle rockets, we had to keep in mind a variety of topics and apply our knowledge of physics in order to be successful in doing so. The competition requires the boundaries of 76 cm for a height value and a 16.5 cm for a radius. Before beginning the complex process of designing an efficient rocket, we looked at previous models for guidance and ideas. We also received instructions from our SECME coordinator. After learning and witnessing what design performs best, we began our construction.
To start with, we used a basic design of two 2-liter bottles. We found that some of the most simplistic designs easily had a longer lasting trajectory, ranging from seven to twelve seconds in air, from some of the more complex designs that only had a maximum of six seconds. To begin with, we cut off ¼ of the total height of one of the 2-liter bottles, or 14 centimeters. We then filled the cut bottle with newspaper. This added weight will serve the purposing of balancing the rocket once in midair and keeping it steady to prevent too much torque, or spin, from occurring. The goal of rocket designing is to balance the weight of the bottle, so that the bottle can reach its maximum hang time. If the bottle endures too much spin, it will not be aerodynamic and will not fly efficiently. Once adding the extra mass of the newspaper, we proceeded to tape the remaining ¾ of the bottle to the whole one. The whole piece serves as the water chamber, where the water will be stored and then exit once the rocket engages flight. The ¾ piece serves, as stated before, as more mass to balance the rocket and provide a steady flight. The whole bottle’s opening is faced downward when gluing on, as the ¾ piece is faced upward, producing two openings in the structure. After developing the basics of the rocket, we continued to make the rocket more aerodynamic to enhance our rocket’s performance.
Our next task would be in designing the nose cone of the rocket. To do so, we used a template designed by our SECME coordinator. The nose cone should be designed out of a thick type of paper; we used manila folders to construct this part. We used an entire sheet of a folder, making the dimensions of the cone to be 20.3 centimeters by 30.5 centimeters, minus the area cut out to make the cone’s shape. After cutting out the cone, we rolled it up and placed it on the top of the ¾-cut part of the bottle, our front. After fitting it, we then taped it on. To finish our design of the rocket’s nose, we added on a paper towel roll with a golf ball placed at the top of it. This is used to serve the same purpose as the newspaper did; it isn’t necessary, but it does enhance the performance because it adds more mass to the structure of the bottle, which balances it. We used a paper towel roll with a length of 22.6 centimeters.
Once finishing the upper parts of the bottle, the only part that remained was to design the fins. The fin design is very significant in the rocket’s flight. When the rocket is descending after reaching its maximum height, it begins to accelerate as it falls back towards Earth due to gravitational force. During the rockets descent, its center of mass begins to move backward due to its loss of water, which presented most of the mass on the journey up. In order to balance the rocket, the fins are placed near the bottom of the rocket. Also, if the fins are designed properly and the conditions are right, gliding may occur rather than a simple vertical, up and down motion of the rocket. Gliding increases the hang time significantly. We found that like the design of our rocket, simplicity works best. We used a triangle-like design for the fins. It measured 5cm on one of its sides, 10.5 cm on the other, and 23cm for its hypotenuse. We then spaced a total of four fins equally over a circumference of 30.48 centimeters. We glued them on and made sure that it was secured to ensure that it wouldn’t fall off the rocket when it’s traveling at a maximum velocity of after designing the fins, nose cone, and structure, our rocket was complete.
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TEAM SILVER Technical Report on Water Bottle Rocket excerpt
Introduction
In the 2009/2010 SECME competition, our mission was to construct an efficient water bottle rocket that could remain airborne for the longest period of hang time. In order to achieve this goal, we had to not only go through the process of trial and error, but also, apply our knowledge of physics. We needed to have a mastery of areas such as aerodynamics, Newton’s Laws of Motion, gravity, acceleration, air resistance, momentum, inertia and the ability to make precise and accurate calculations and plan each step accordingly. In the process of building these rockets, we enhanced our life skills, such as responsibility, hard work, teamwork, and of course, ingenuity.
Design Background
In the process of building the water bottle rockets, we had to keep in mind a variety of topics and apply our knowledge of physics in order to be successful in doing so. The competition requires the boundaries of 76 cm for a height value and a 16.5 cm for a radius. Before beginning the complex process of designing an efficient rocket, we looked at previous models for guidance and ideas. We also received instructions from our SECME coordinator. After learning and witnessing what design performs best, we began our construction.
To start with, we used a basic design of two 2-liter bottles. We found that some of the most simplistic designs easily had a longer lasting trajectory, ranging from seven to twelve seconds in air, from some of the more complex designs that only had a maximum of six seconds. To begin with, we cut off ¼ of the total height of one of the 2-liter bottles, or 14 centimeters. We then filled the cut bottle with newspaper. This added weight will serve the purposing of balancing the rocket once in midair and keeping it steady to prevent too much torque, or spin, from occurring. The goal of rocket designing is to balance the weight of the bottle, so that the bottle can reach its maximum hang time. If the bottle endures too much spin, it will not be aerodynamic and will not fly efficiently. Once adding the extra mass of the newspaper, we proceeded to tape the remaining ¾ of the bottle to the whole one. The whole piece serves as the water chamber, where the water will be stored and then exit once the rocket engages flight. The ¾ piece serves, as stated before, as more mass to balance the rocket and provide a steady flight. The whole bottle’s opening is faced downward when gluing on, as the ¾ piece is faced upward, producing two openings in the structure. After developing the basics of the rocket, we continued to make the rocket more aerodynamic to enhance our rocket’s performance.
Our next task would be in designing the nose cone of the rocket. To do so, we used a template designed by our SECME coordinator. The nose cone should be designed out of a thick type of paper; we used manila folders to construct this part. We used an entire sheet of a folder, making the dimensions of the cone to be 20.3 centimeters by 30.5 centimeters, minus the area cut out to make the cone’s shape. After cutting out the cone, we rolled it up and placed it on the top of the ¾-cut part of the bottle, our front. After fitting it, we then taped it on. To finish our design of the rocket’s nose, we added on a paper towel roll with a golf ball placed at the top of it. This is used to serve the same purpose as the newspaper did; it isn’t necessary, but it does enhance the performance because it adds more mass to the structure of the bottle, which balances it. We used a paper towel roll with a length of 22.6 centimeters.
Once finishing the upper parts of the bottle, the only part that remained was to design the fins. The fin design is very significant in the rocket’s flight. When the rocket is descending after reaching its maximum height, it begins to accelerate as it falls back towards Earth due to gravitational force. During the rockets descent, its center of mass begins to move backward due to its loss of water, which presented most of the mass on the journey up. In order to balance the rocket, the fins are placed near the bottom of the rocket. Also, if the fins are designed properly and the conditions are right, gliding may occur rather than a simple vertical, up and down motion of the rocket. Gliding increases the hang time significantly. We found that like the design of our rocket, simplicity works best. We used a triangle-like design for the fins. It measured 5cm on one of its sides, 10.5 cm on the other, and 23cm for its hypotenuse. We then spaced a total of four fins equally over a circumference of 30.48 centimeters. We glued them on and made sure that it was secured to ensure that it wouldn’t fall off the rocket when it’s traveling at a maximum velocity of after designing the fins, nose cone, and structure, our rocket was complete.
Thursday, December 3, 2009
Citations
WATER BOTTLE ROCKET
While talking with a caller about air pressure, the Magic School Bus producer is unaware that Liz is creating a bottle rocket using air and water to launch the bottle.
http://player.discoveryeducation.com/index.cfm?guidAssetId=0D940983-C5A6-4986-9467-13978975C84&blnFromSearch=1&productcode=US
Citation (APA)
Combining Air and Water. Scholastic.
(1997). Retrieved December 2, 2009, from
Discovery Education: http://streaming.discoveryeducation.com/
MOUSETRAP VEHICLE
The most up-to-date and informative mousetrap powered car manual ever written with all new earth-shattering secrets for 2009. Selected by students and teachers world wide as the best resource available for learning how to build winning mouse trap powered racer. Learn how to build the ultimate speed-trap dragsters, long distance racers, boats and more with easy to follow step-by-step plans written for beginners and seasoned veterans alike. This book is designed to eliminate the guesswork! Mousetrap Cars: The Secrets to Success includes over 159 pages of secret construction tips, instructions, design plans, formulas, experiments, and more.
Citation (APA)
Balmer, A. (1996). Mousetrap Car Plans: The Secrets to Success.
(1996). Retrieved December 2, 2009, from Doc Fizzix Mousetrap Racers website: http://www.docfizzix.com/pdf-files/MTV-secrets-sample.pdf
While talking with a caller about air pressure, the Magic School Bus producer is unaware that Liz is creating a bottle rocket using air and water to launch the bottle.
http://player.discoveryeducation.com/index.cfm?guidAssetId=0D940983-C5A6-4986-9467-13978975C84&blnFromSearch=1&productcode=US
Citation (APA)
Combining Air and Water. Scholastic.
(1997). Retrieved December 2, 2009, from
Discovery Education: http://streaming.discoveryeducation.com/
MOUSETRAP VEHICLE
The most up-to-date and informative mousetrap powered car manual ever written with all new earth-shattering secrets for 2009. Selected by students and teachers world wide as the best resource available for learning how to build winning mouse trap powered racer. Learn how to build the ultimate speed-trap dragsters, long distance racers, boats and more with easy to follow step-by-step plans written for beginners and seasoned veterans alike. This book is designed to eliminate the guesswork! Mousetrap Cars: The Secrets to Success includes over 159 pages of secret construction tips, instructions, design plans, formulas, experiments, and more.
Citation (APA)
Balmer, A. (1996). Mousetrap Car Plans: The Secrets to Success.
(1996). Retrieved December 2, 2009, from Doc Fizzix Mousetrap Racers website: http://www.docfizzix.com/pdf-files/MTV-secrets-sample.pdf
Wednesday, December 2, 2009
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