Hyundai is looking for the next big thing in the car industry, and they are asking STEM Marin for help! For the past few weeks, we have been working on creating a car using an alternative energy source, as well as having a presentation to help sell our product. The car had to travel five meters while holding 250 g or "cargo." In the beginning of this project, we had a totally different idea. Originally, we were going to build a metal car with an air-tight device that used compressed air as an energy source, with many small attached wooden pieces. One problem was that there were very many small pieces of wood that needed to have even smaller, precise holes drilled into them. The device also had to be airtight. As you can tell, this idea was very complicated, thus running into problems was almost inevitable. So after taking very precise measurements, drilling, and gluing, our contraption didn't end up being airtight. So, we had to brainstorm another idea. After considering different energy sources and frames for the car, we came up with The Hipster Mobile. Our car was made out of 4 colored pencils for the axles, one piece of larger wood and two pieces of smaller wood for the body, four compact disks for the wheels, two rubber bands for our energy source, and two nails to hold the rubber bands in place. To get our car to travel five meters, we tied one end of the rubber bands to the front axles and wrapped the other end around nails in the back of the car. On our first attempt, the wheels kept spinning, while the car went nowhere. We knew that there was too little friction from the slippery wheels and floor, so to fix this problem, we added tape to the wheels so they would stick to the floor and propel the car forward. After a few attempts and some tweaking, we finally got our prototype to work consistently. After perfecting our automobile, we had to make a presentation to sell our prototype to Hyundai. (see link above)
Reflection
I think that overall, this project went fairly well. My group worked well together, but there are some things we could have improved on. Our first major pit was time management. Even though we had written down what we needed to accomplish each day on a calendar, we still struggled. Another pit of this assignment was our first idea not working. The main reason we were rushed toward the end of the project was because we spent so much time trying to build and tweak the air cylinder, but when we were finally finished, it didn't even work. We wasted about three to four days working on that device, causing us to loose a many valuable work hours. Although we ran into problems, we had some peaks over the length of the project too. One of them was our ability to quickly think of new ideas and start building the new car. As soon as we knew what our new plan was, we got right to work. Another peak we had was our ability to quickly identify the problems we encountered and solve them. For example, our car wasn't going far enough, so we decreased the number of rubber bands we were using to increase the tension. Also, the weights would keep falling of the car, so we put them by the wheels to prevent them from toppling over while our prototype was in motion. Some things I did well during this project were helping to keep my group on track. Once in a while we would get distracted, and I would nicely remind my group members to get back on track. Another thing I did well was to write down all the information for the presentation. We would always need to refer back to my notes in order to construct the presentation. Something I could improve on for next time is making sure my group's idea is actually attainable in the amount of time given. This way, we could avoid wasting time on a product that won't end up working. One final improvement for next time is keeping track of time left to work, in order to leave enough time to create both the model itself and the presentation. This project ended up working very well in the end, and I'm glad it went the way it did!
Content
total energy-the total amount of energy (used in the total energy graph) potential energy-(m=mgh J) energy of position (used in total energy graph) kinetic energy-(ke/pe=1/2mv^2 J) energy of motion (used in total energy graph) thermal energy-(J) heat energy (used in total energy graph) acceleration-(a=vt m/s^2) the rate at which velocity is changing (to calculate acceleration of car) speed-(speed=d/t) how fast something is moving (to calculate top speed of car) spring constant-(f=kx and mg=kx) a measure of the elasticity of spring (used to measure how much energy the rubber band had) spring potential energy-(pe=1/2kx^2) energy due to compression or expansion of elastic pe friction- force that affects motion (helped our car move better due to the wheels gripping the ground) elastic energy-(J)energy stored in the stretch/compression of an elastic substance. we found this out by measuring how many times the band was wound around the front axle at each meter pressure-(Pa) amount of force exerted on a given area power-(w) rate of which work is exerted. our car had a lot of power
Do it Better
For our do it better project, we had to choose a previous project and "do it better." Citlalli, Camille, Bella and I decided to make a car, which we called . Our car is made using one large piece of wood for the frame, four small pieces of wood to attach the axles, which are made of a copper pipe and a pencil, 10 CD's wrapped in rubber for the back wheels, two plastic wheels covered in rubber bands for the front wheels, and four zip ties to keep the front wheels from moving. We used the idea from my car to use rubber bands as our energy source. We had a nail on the wooden frame of our car that we put one end of the rubber band around and we tied the other end around the back wheel's axles. To make the wheels spin, we rotated the back wheels slowly so the rubber bands' tension increased as they wound around the cylinder. When we released the wheels, the tension quickly decreased, causing the wheels to spin and the car to propel forward. We ran into some problems such as wobbly wheels, splitting wood, and not enough power, but we fixed these issues to the best of our ability. Below is a video of our car in action:
Reflection
This project was very fun and relaxed. There were many things that went well but also some things we struggled with. We had a hard time getting started, we spent a lot of time trying to figure out how we should start. Something else we could have improved was not dwelling on the problems we encountered. We split our wood, and one of our wheels was a little crooked, and we should have tried to fix the issued instead of thinking about what we should have done instead. Both of these pits consumed precious time that we didn't have, since this was such a short project. Some high points were our ability to stay focused, which we improved from last time. We were also very at evenly distributing the work. For example, two of us would be working on the frame while the other two were painting the wheels. This was a very efficient way to get work done faster. I feel like I could have helped to get the project going a little faster, but that is something I will improve for next time. Personally, I feel this car didn't quite reach the standards of my previous one, but we worked as hard as we could to make the best product possible.