Science: Physics Experiment 2
In Science class we are studying physics and right now we are looking at Newtons three laws and speed. All of us chose cars to put on a track and time. I looked at the cars that we brought in and guessed which one was the fastest. I chose the smallest car because I thought that it would have the least resistance. I pretty much ignored the fact that if something heavy gets going it is harder to stop. The car that I chose is a Porsche Carrera. To calculate the time my group built a track that was 275 inches long. To time the cars I sat at the end of the track with a stopwatch and put my arm across the track so that as soon as I felt the car I could stop the timer. My car’s average time to get across the whole track was 2.23 seconds. That’s about 123.4 inches per second. That is 7.00 MPH. My car went the fastest and I think that is because it was really small so the launcher could get it going fast, then the wheels spun really easily so it could keep going at top speed the whole time. The other group had a much shorter track than us, only eight feet, so their cars went faster because there was not enough time for them to slow down.
For my group experiment I decided I wanted to find an equation for speed in relation to slope of a track. My hypothesis for our experiment was that the steeper the track was the faster the car would go. This is pretty much what happened but we made a mistake in our experimenting. We often changed the track length after the slope so the cars would slow down and change our results. If I were to do this experiment again I would have had a length of track that I would have used every time and I would have made sure that the parts of the track that are not sloped are the same length every time. This way the measurements would be more accurate. All of our tracks were almost the same length except one were we made the sloped part really long and it made the cars go a lot faster. This was the case on our last round of testing and it shows in the data. I put the data into an Excel with help from Carwai. We used the slope and the inches per second to make a graph to find our equation. It helped us achieve our goal of finding an equation to calculate speed of a car after it comes off of a slope. The equation is y=18.54x + 103. It should have been around y=18.54x + 78 though. This is because the last time we ran a test we made the ramp much longer which made the cars go faster and made a spike in our graph.
Our group was not very productive at first. I think that it was because of the cars and ramps. We didn’t have a question that we wanted to answer. We had a test that we needed to find a question for. I felt frustrated at times when we needed to move on but the rest of my group was still playing with the cars. Our group often became distracted by the cars and ramps so I had to work hard to get their attention. When we started writing about our project my group asked me at least four times what the purpose of our experiment was. It was partially my fault for not telling them before we started our first round of testing. I told them during it and they did not hear me because of how excited they were about the cars. I was having fun too but they definitely got too distracted at times. Which was also a little bit frustrating but in the end I think that all of them figured out what needed to happen, because they all sat down and wrote for a long time. We took some cool videos of our cars going down a track but we haven’t put that together yet.
