Rube Goldberg EF 151 Project

Transcription

1 4/26/2010 Team Number 7 Class B1 Rube Goldberg EF 151 Project John Shin Matt Dischner Jacob Price Rob Baldus

2 Abstract: What we are trying to accomplish with our Rube Goldberg device is the ability for it to be started by another team s device and then be able to start yet another team s device as well. For us to do this, we had to collaborate with other teams and keep their devices in mind while we developed our own. If our calculations are correct, we should theoretically be able to accomplish our goal. The device runs very smoothly and has no flaws in its design. Introduction: The main objective of this engineering project is to work within a small group to make a Rube Goldberg device that will successfully complete a collective circuit of devices provided by other teams. Our device has the option of being started manually and starting the circuit which will begin the other group s devices or of being started by another group s device. Our project should be able to both. Our device is able to complete itself through translational energy, rotational energy, conservation of linear momentum, and conservation of angular momentum. Device description: Our Rube Goldberg sits entirely on an 18.5 inch x 18.5 inch base of wood and is 29 inches at its maximum height. It can be started manually or automatically by acting on a mousetrap, which is the first component of our device. The mousetrap then triggers a springloaded toy device that hits a bottle cap into a heavy metal magnet. This metal magnet falls off a block of wood onto another mouse trap that is attached to a wooden pivot by a copper wire. When the second mouse trap is triggered, the wooden pivot which it is attached to, whips around with an angular velocity into a metal ball at the top of a tunnel of plastic tubing. The ball falls

3 down the tube, and strikes another magnet which soars into a metal basket that is attached by string to a switch. Once the ball falls into the basket, the weight pulls the switch which is attached to a battery powered motor that turns a gear. This gear system is attached to a rod which is in turn attached to a string. The other side of the string is connected to a track that has a metal ball on it and is parallel to the ground. When the ball activates the motor, the gear turns the rod and the rod lifts the track which allows for the metal ball to fall through a hole in the track. This ball falls into a funnel where two screws lay in the bottom. The two screws are connected to circuits of a toy and when the ball falls and touches the screws, the circuit to power the toy is completed. The toy is then able to activate another group s device or another electronic device. Equations: So in the first part of our Rube Goldberg device, we have the wooden pivot knocking into the ball. We had to find the angular velocity pivot which is turned by the mouse trap with a spring constant =.0778 N x m / rad. The mousetrap has a radius.0737 meters. Because we have the radius of the mousetrap, we can solve for the x distance travelled by the mouse trap which is m. We find the energy lost by the mousetrap with the equation 1 2 kx2 = energy lost We find the energy to be J. We have the mass of the block as.04 kg and the dimensions of the block as.23 m x.0165 m. We then need to solve for the mass moment of inertia of the wooden pivot so that we can find the angular velocity of the wooden pivot Mass moment of Inertia = 1 12 m(a2 + b 2 ) The mass moment of inertia is kg x m^2. Now, because we have mass moment of inertia and energy loss, we can solve for angular velocity of the block with the equation

4 Energy loss = 1 2 Iω2 We find angular velocity of the wooden pivot to be rad. / s. To find the speed of the metal bearing at the bottom of the tube after it has been struck by the wooden pivot, we use the equation 1 2 mv mg 1 = 1 2 mv f 2 + mg f Iω2 The velocity of the ball at the end of the tube is m / s. We use this velocity to measure the speed of the magnet and ball after they collide at the bottom of the tubing. The mass of the ball is.015 kg and the mass of the magnet is.1 kg. To solve for the velocity after the collision, we used the equation M ball V ball = (M magnet + M ball )V f The final velocity after his collision is m / s. Bill of Materials: Mouse Traps $.50 Wood $8 Tubing $2 Hardware $3 Toy Motors $5 Duct Tape $1 Metal Balls $.25 Copper Wire $.25 Results:

5 The device was thought of by Robert and perfected by Matt. The Rube Goldberg contraption is very efficient, rarely malfunctioning. Through many trials, we have figured out how to complete its circuit without much error. Some problems arise if the device is not set up properly, however. The gears that rotate and lift the track have to be precisely attached so that the gears do not slip off each other when the motor is started. Other than that problem, the Rube Goldberg device is perfect and will not fail. Conclusion: The Rube Goldberg device was able to work efficiently consistently. There were few to no errors when the device was started. We were also able to calculate somewhat accurately the physics that allowed our device to function. References: For references, we used mostly used the EF151 final project website. In order to do the math for our project, we frequently referred to the EF151 modules.

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