For the past month, my class has been working on building a Rube Goldberg Machine. This type of machine involves a series of complicated steps that have a very simple end result. Our final product was to have a cup with a tea bag in it and make tea using water and sugar cubes. My group first made a blueprint of all of our steps, made some final adjustments, and started building right away. Our machine had to include at least ten steps, five simple machines, and four energy transfers. My Rube Goldberg started out by releasing a wedge which caused a soccer ball to roll down an inclined plane, which then hit a lever that caused two balls, a marble and a golf ball, to roll down another inclined plane. A unique factor about our machine was that it had two different paths going on at once, instead of just one. So, the marble, after falling through a small hole in the second inclined plane, would go down a series of three more inclined planes, hit sugar cubes, and cause them to fall into the cup. While this was going on, the golf ball would also fall through a hole in the second inclined plane and activate a pulley. The pulley would cause a wedge to lift up, which knocked over a cup of water into a screw that led into the cup with the sugar and tea bag. After constructing our machine, we made a presentation that included all the calculations of the physics involved, the schematics of the project, and an oral presentation. Altogether, we had about 22 hours to build and perfect our project and presentation.
Reflection
Overall, I think my group did very well in all aspects of the project, although there were some things we could have worked on. One major pit in my group was time management. We ended up spending a lot of time building and tweaking small parts of the project. This is because we were an all-girl group, which meant we didn't have much experience using power tools. It took us a few days to really learn how to use the different tools and adjust to them, but once we did, we knew what we were doing. Because of this setback, we didn't have much time to work on or practice the presentation part of the project. Next time, we could make a type of schedule that showed what we should try to get done every day in order to have enough time for everything. Another pit we encountered was the amount of work each person did. I realized that throughout the build time, we had people sitting around while one person worked on something. In the future, I would like to split into pairs and make sure everyone is always working on something, so we can accomplish tasks quicker. I also noticed some improvements as we progressed further into the month. For example, a peak was that my group learned to communicate very well and work well with each other. We always listened to everyone's ideas and inputs and stayed positive. I realized that this helped everything go very smoothly as we continued to work. A second peak I realized was that I, along with the others in my group, improved on our speaking skills. When I first tried to present my project, I was very nervous and tended to look down, talk quietly, and use filler words. But, as I got advice from my peers continued to practice, I became more confident whenever I ran through the oral presentation, and by the time STEM night came around, I was very well prepared.
Concepts
Step 1: Lift up the wedge on which the ball is exerting a force of 0.4921 N. Force is a push or pull, and can be calculated by multiplying mass times acceleration. The unit used is Newtons. (F=ma). Step 2: The soccer ball rolls down a second inclined plane with a force of 0.4928 N. Step 3: The soccer ball hits the lever with a force of 4.503 N. Step 4: The lever causes the golf ball and marble to roll down the second inclined plane and transfers kinetic energy to potential energy. Step 5: Both balls had a change in potential energy, which is the energy of position, usually related to the relative position of two things . It is calculated by multiplying mass, acceleration due to gravity (9.8m/s^2), and height. The unit used it Joules. (P=mgh) The golf ball had a change in potential energy of 0.0495 J, and the marble had a change in potential energy of 0.00065 J. Step 6: The marble travels down two inclined planes. The first has a velocity of 0.3123 m/s and the second had a velocity of 0.66 m/s. Velocity is speed with a given direction. It is calculated by diving distance over time. The unit used is meters per second. (V=d/t). Step 7: The golf ball rolls down a lego inclined plane that has a mechanical advantage of 0.0101 N. Mechanical advantage is the ratio of output force to input force for a machine. You can use the equations output force/input force or input distance/output distance. There is no unit for MA. Step 8: The marble rolls onto another inclined plane with a certain acceleration. Acceleration is the rate at which velocity is changing. It is calculated by dividing the change in velocity by the change in time. The unit used is m/s^2 (A=v/t). Step 9: The golf ball falls into the cup with a certain velocity and activates the pulley which has a mechanical advantage of 1. Step 10: The pulley lifts the wedge with a MA of 1. Step 11: The water falls down the screw and into the cup which has a potential kinetic energy of 0.418 J. Kinetic energy is the energy of motion. It is calculated by multiplying 1/2 mass times velocity squared. The unit used is Joules. (KE/PE=1/2mv^2). Step 12: The marble rolls down a final inclined plane with a momentum of 0.000675 kgm/s and knocks the sugar cubes into the cup. Momentum is the product of the mass and velocity of an object. It is calculated by multiplying mass times velocity. The unit used is kgm/s. (M=mv). Step 13: The tea is made!
Additional Concepts
Speed: Speed is how fast something is moving. This is calculated by dividing the distance by the time. The unit used is meters per second. (Speed=d/t). Impulse: Impulse is the product of force and time interval during which the force acts. It is calculated by multiplying force by time. The unit used is kgm/s. (Impulse=Ft). Work: Work is the product of the force on an object and the distance through which the object is moved. Work is calculated by multiplying force times distance. The unit used is a Joules. (W=fd).