A Rube Goldberg Machine is a machine built to complete many complex steps to have one simple end result. In our machine we had eleven complex steps that resulted in mentos falling in to coke. My group spent about 30 hours on this project and four weeks working hard to reach the deadline. In this project we demonstrated concepts such as Potential Energy and Kinetic Energy. We also learned about energy transfers, mechanical advantage, force, velocity, and work.
CONTENT:
Velocity:
Velocity is the rate of distance covered in a direction. You can find velocity by dividing distance by time. In my project I used velocity to find how fast the ball was rolling down the first lever. I first found how long it took the ball to roll down the inclined plane. Then I measure how long the distance was from the start of the incline plane to the end of the plane. I took distance which was 0.4 meter and divided it by 0.6 seconds to find the average velocity which was 0.66 meters per second. I then took the average velocity, and multiplied it by two to find the final velocity. I also used velocity to find how fast the mentos was falling before it landed in the coke. I first measured the distance from the can to the trap door. I then figured out how long to took for the mentos to fall into the can using a stopwatch. I took the distance which was 0.4 meters and the time which was 0.3 seconds and divided them. My answer was 1.3 meters per second for the average velocity and the final velocity was around 1.7 meters per second.
Acceleration:
Acceleration is the rate of change in velocity speeding or slowing down. To find acceleration you divide the change in velocity by the change in time. Acceleration can also be found be dividing acceleration due to gravity by the mechanical advantage of the incline plane. The unit acceleration is in is meters per second squared. In my project I found the acceleration of the ball rolling down the second lever. I first had to find the mechanical advantage of the lever. To do so I had to divide the length of the lever which was 0.3 meters and divided that by the height of he lever which was 0.15 meters. The answer I got was 2. I then took the acceleration due to gravity which is 9.8 meters per second squared and divided it by 2. The solution I found was 4.9 , which means the ball was rolling down the incline plane with an acceleration of 4.9 meters per second squared.
Mechanical Advantage:
Mechanical Advantage is how much easier a tool makes something happen. Mechanical advantage was found in our first incline plane, the incline plane right after the pegboard, in the pulleys, in the screw and the dart tip. In all of these cases except for the dart tip, to find the mechanical advantage you had to take the length divided by the height. In the dart tip to find the mechanical advantage you had to divide the length by the width.
Force:
Force is a push or pull on an object that usually causes a change in motion. Force is measured in Newtons and is found by multiplying the mass times acceleration. In my project I found the force of the weight exerted on the trigger of the Nerf gun. To find the exact force I multiplied 9.8 meters per second times 1 kilogram which gave me 9.8 Newtons. Since the weight is not free falling it was sliding on a incline plane I had to take the 9.8 Newtons and divide it by the mechanical advantage of the slope which was 1.67. After I solved the problem I figured out that the force exerted on the nerf gun by the weight was 5.9 Newtons.
Potential Energy:
Potential Energy is energy an object has due to its position at a height. Potential energy if measured in Joules and is found by multiplying the mass times the acceleration due to gravity times the height. In our project we found the potential energy of ball resting in the balloon. We found this by multiplying 0.28 kilograms by 9.8 meters per second squared by 0.15 meters. The end result of this problem is 0.4 Joules.
Kinetic Energy:
Kinetic Energy is energy due to motion of any kind. To find Kinetic Energy you have to multiply the mass and velocity squared. Once you get that answer you have to half it to get your final answer in Joules. In our project, we found the kinetic energy of the mentos right before it lands into the can of coke. Since the formula for kinetic energy requires velocity, we needed to find the velocity of the mentos. To do this we divided 0.4 meters by 0.3 seconds to get a final answer of 1.3 meters per second. Then I had to multiply that answer by two to get the final velocity which is 1.7 meters per second. I then had all the necessary variables I could solve the problem. I took 0.03 kilograms and multiplied it by 1.7 meters per second squared. Then took 0.087 and divided it by a half to get 0.17 Joules.
Work:
Work is the amount of energy put onto something. Work is found by multiplying force times the distance and is also measured in Joules. In my project, we found the work of the weight about to pull on the trapdoor. Since we didn't have the force of the weight and work equals potential energy which equals kinetic energy my group used the potential energy formula to find the work. We took 0.05 kilograms times 9.8 meters per second squared times 0.15 meters. The answer to that was 0.74 Joules which means the work of the weight is 0.74 Joules.
REFLECTION:
I not only learned many physics concepts and how to make this machine, but I also learned many group skills. I learned that sometimes you have to step up as the leader and take charge. While other times I have to step down and let others lead. I also learned how to keep everyone on task and make sure work is getting done.
There were two main "pits" or downfalls my group had. First, one problem my group had was keeping on task. I think this was a pit many groups had, but I think my group solved the problem very well. Other than avoiding the problem we assessed it immediately. We noticed in the first couple of days that we were having trouble staying on task, so we quickly came to a solution. Our solution was we appointed a group task manager that made sure everyone was doing their job. Our next pit was, being too social. The task manager's job was to also make sure we stayed in our group. Sometimes one person in our group would wonder off and the task manager would have to tell them to come back.
The two main "peaks" or something gained I had was learning when to take charge and when to step back. I would have to take charge when people in my group weren't paying attention. I would also have to get everyone back on task and make sure we would finish on time. I would have to step back and let others take charge many times too. I would do this to make sure everyone's voice was heard and every idea was spoken of.
In the end, I was very happy with our project and felt that we spent our time well. I know that our machine doesn't work 100% of the time, but that helps with the learning process. I am very happy with how our project turned out, and can't wait to do it again senior year.