Rube Goldberg Project

Abstract

The objective of this project was to practice our ability to build a machine that could carry out a certain objective. This machine was required to include a minumim of five steps total, with a minimum of three simple machines. Every aspect of the machine was to stay in the parameters of the 5'*5'*2' area given as the allowed space. Any particles or materials that would be unattached or free falling (i.e. marbles, water droplets, etc.) must remain within the space. We were required to document our progress and any changes we made to the machine as we designed and built it. We built a machine that would push the button on a digital camera to take a picture. Our machine included an inclined plane, followed by a pulley, initiating the use of another incined plane, which would be followed by a first class lever that would start another pulley, pushing the camera's button.

Introduction

The purpose of the Rube-Goldberg project is to learn how to work well in a team, while applying our knowledge of simple machines in order to build a complex set of machines. The purpose is also to create a design that we have brainstormed and make it work, while making changes in the process. We will learn how to better organize our progress and work in our journal. Our group decided to make a Rube-Goldberg that would take a picture.

Background

In order to accomplish the task of creating a Rube-Goldberg machine, there was quite a bit of information which had to be gathered before construction could begin. This information consisted of the requirements which the machine have to have. The Rube-Goldberg machine had to be made up of, but not limited to, five steps and three simple machines (pulleys, levers, and planes) and be no longer than 5ft. With this information, construction of the Rube-Goldberg machine began. After researching other ways in which such machines have been created the method of creating our machine differed greatly than others. This difference came mainly with the construction. Many designs were built with complex objects such as lego pieces, styrofoam, or PBC pipes and our machine consisted mainly of wood, string and cardboard. This is what makes our creation different from others.

Below is the process of the machine

Step one: the ball rolls along the edge of the box

Step two: the ball falls into the box

Step three: the flap connecting the string to the box raises and drops the second ball

Step four: the ball rolls down a ramp and into a cardboard wall

Step five: the cardboard wall falls onto a lever

Step six: the opposite side of the lever rises

Step seven: the raised lever causes the string to fall, placing a weight on the camera and pressing the "click" button.

As the ball begins rolling its way along the edge of the box, it has potential energy, then as it drops into the box it has kinetic energy, which is then transferred to the box, causing the box to drop the same rate as the ball did as it hit the box. After this action the flap raises up causing the ball to fall down a ramp. During this time, the ball and the flap have potential energy, but after the ball falls, it has kinetic energy and then this energy is restored back to potential when the ball comes to a stop after hitting the cardboard wall. The ball transfers its kinetic energy into the cardboard wall, causing it to fall onto a lever. Before the wall falls onto the lever, the lever has potential energy as it rests, waiting for an outside force to be acted upon it. The kinetic energy in the lever causes it to rise and then this energy is transferred to the weight, which is placed above the camera. After the weight falls onto the camera, its kinetic energy is restored back to potential energy.

Materials

• Cardboard
• 4x pulleys
• 2x golf balls
• wood
• fishing string, cotton string
• camera
• paper
• tape
• hot glue
• curtain rod

Procedure

• Create a rough draft of how the design should be built.
• Create a materials list and divide each item for each team member to bring.
• Build inclined planes and levers.
• Place a plane on the edge of the big box for the ball to roll off of.
• Create a small box for the ball to fall into after it's rolled off the plane.
• Build a ramp with a flap connected to it's top edge.
• Attach a string from the small box to the flap that's on the ramp.
• Place a second ball on the flap.
• Originally the second ball was going to roll down the ramp and into some Jenga blocks, but this plan didn't work well, so the Jenga blocks were replace by a cardboard wall.
• Place the lever that was made earlier in front of the cardboard wall.
• On the other side of the lever, attach a string to it.
• This string is placed in a pulley, which is attached to a curtian rod, which is attached to a bigger carboard box that is laid out infront of the lever.
• After passing the string through the pulley, weights are then tied to the end of it.
• These weights are then placed a few inches above the camera's "click" button so that when the weight drops, it will land on the button.
• In the original plan there were three levers, but this would be hard to make, so two levers were omitted.
• In the rough draft of the design there were three balls to be used, but this number got reduced to two. The third ball was replaced by string.

Mechanical advantage

Simple machines are made to make things in every day life more simple to do. Simple machines include: first, second and third class levers, inclined planes, pulley systems, a wheel and axle, a screw, and a wedge. Without these, life would be much more difficult and we would not be able to have many of the opportunities and privileges we are fortuned to. A hammer, a door knob, a bicycle, and a see-saw are all examples of simple machines.

To calculate the ideal mechanical advantage of an object, the effort, resistance, length from the effort to the fulcrum, and the length from the resistance to the fulcrum must be found. Mechanical advantage is the resistance force divided by the effort force, or the length from the fulcrum to the effort divided by the length from the fulcrum to the resistance. This is the formula for a lever. To find the mechanical advantage of a pulley, the total number of strands supporting the load must be found. The formula for the mechanical advantage of an inclined plane or wedge, is the slope length divided by the height of the inclined plane or the thickness of the wedge. The mechanical advantage of a screw is the circumference of the screw divided by the pitch of the threads on the screw. To calculate pitch, 1 is divided by the threads the screw has per inch. The mechanical advantage of a wheel is the wheel radius divided by the axle radius. For this project two inclined planes, two pulleys, and a first class lever were used. Because the machine was unable to perform properly, the mechanical advantage for each simple machine wasn't calculated. However, each simple machine worked with the exception of the last pulley, which was unabled to be positioned correctly to where it would hit the camera's "click" button.

Results

In the end the machine was unable to take a picture, but everything leading up to the pushing of the camera's button worked as expected. On the test trial, the machine ran its course, but when the golf ball hit the ramp to lower the weight, to push the camera's button, the weight didn't push the button accurately to take the picture. A couple of changes were made to compensate for time and complexity. Initially the starting ball was going to be launched from a catapult, but this would make the design way too complex. For the most part, the design was the same from the rough drafts. The part which was going to hit the camera button could have been given more support by connecting rubber bands from the weight to the camera, so it would have had more pressure to pull the weight down.

Conclusion

We learned that it is necessary to try a variety of ways to do something before being successful. After trying multiple times to make the first class lever and pulley combination work, we realized that we would have to add a few things and take things away from the machine. We learned that it is necessary to be as accurate as possible when building such a comples machine, but most importantly we learned to work as a team.

References

No references were used for this project. Everything was personally designed. A Kodak 9.2 megapixel digital camera was used. All other materials wer scrap (i.e. cardboard, wood, golf balls, etc.). No research was necessary for this project.