On One Day, I participated in the rollercoaster group and created a car that was supposed to go over the slope. My goal was to build a race car that could go fast enough to go over the slope. I chose to do the rollercoaster group because I wanted to do some engineering and learn how to use different tools.
I started off my design process by researching the aerodynamics of a car from http://www.buildyourownracecar.com/race-car-aerodynamics-basics-and-design/. Next, to give me some inspirations, I searched for gravity cars on google and chose some models to base my car off. I started off the building of my car by making all my measurements and drawing a quick model on the table to give me a basic idea of my car. I then drew out all the sides of my car with a pen so when I cut it with an exact-o-knife it would be straight and exact. To put my pieces together I used hot glue. After my first try, my car broke so I needed to fix it. I just fixed the wheel back on and tried again, but it didn’t work again, so I needed to take another plan of action. I changed my wheels and took off the rubber around it so it was sleeker and could go faster. I then put on a fin on the back because there were many examples of gravity cars that had fins.
Some of the problems I had was my car didn’t run straight, it wasn’t heavy enough, it kept falling apart, and it wasn’t fast enough to get over the slope. To solve my problem of my car not running straight, I realized my axels weren’t straight, so my wheels went in different directions, making it move diagonally. When I first glued my wheels and axels on, I used a lot of glue, so when I tried to take it off, they were glued on too hard. To solve that, I just cut off the edges of the straw and got new straws to make new wheels and axels. To make sure I placed them straight, I measured with a ruler to make it even on both sides so both sets of wheels would be parallel to each other. When my car wasn’t heavy enough I glued on six rocks onto the inside of the car. After I finished gluing four rocks, it was a bit heavier on the left, so I had to glue on two more rocks closer to right to balance it out. My wheels and sides kept falling apart, so I used duct tape to make it more secure. The duct tape was really effective, because when my car fell of the tracks it didn’t fall apart anymore. My car couldn’t go over the slope because it wasn’t fast enough, so I searched for gravity cars with fins, because I was advised to try fins on my car. Then, I saw many people took of the rubber off their wheels, and when I tried rolling my car with them off, they seemed to move a lot faster, so I took off the rubber. When I tried my car with a fixed axel, rocks, a fin, and no rubber on the wheels, it managed to go over the slope.
I think next time when I make a gravity car, I will put less hot glue because it was a big challenge for me to try to take pieces apart and if I put more hot glue on the sides of my pieces to make it stick better, it took up more space, so when I tried to take it apart and failed, it was harder to fix my problem. Also, if I do it next time, I will duct tape my rocks to the car, because the rocks that were hot glued came off inside the car. The problem was, I couldn’t fix it and stick it on again because I would have to take off the top, and it was secured tightly with duct tape, so if I took it off, I would probably rip my car and would have to start over again. The rocks made it slightly more difficult for my car to go over the slope because it messed with the car’s balance.