Energy, Astronomy, Lasers

The bouncing ball graph. Click to enlarge.

Classes began with conservation laws. Even though I had learned these before, it was useful to have a quick refresher. To illustrate these laws, we did a bouncing ball lab. We dropped a ball under a motion sensor. The computer recorded its position as it bounced. We were then able to create graphs of kinetic and potential energy. As the graphs only tracked energy based on position (kinetic energy and gravitational potential energy in this case), total energy (the red line) appears to decrease. However, with each bounce, the energy is being dissipated into sound and heat, so the total energy that is tracked goes down after each bounce. During the middle of the bounce, the energy stays constant as you might expect. The reason the total energy appears to dip almost to zero in each bounce is because the device does not track elastic potential energy, the energy stored as the ball deforms before it springs back up. Next up: a guest speaker.

Jim Aguirre is a researcher at Penn. He is involved in radio astronomy. He began by telling us about how stars clump together into galaxies, then how galaxies are grouped. He told us about dark energy, dark matter, and the universe expanding. He then talked about how we measure the universe, and how we can tell how far away things are. He covered a wide variety of things about the universe and astronomy in general before he explained about his personal research. His plan is to have an enormous quantity of smaller sensors, instead of one super massive dish. This is much cheaper, but can still provide an incredible amount of data.  Overall, I thought that this was a great lecture. He delved deep into the concepts without getting bogged down in complex equations and vocabulary. Even though almost all of it was easily understandable, he provided interesting ideas and theories. 

After the guest speaker, it was time for lunch. On the walk there, I talked to a fellow student a bit. He told me about photometry. Interestingly enough, the units are not derived from the standard kilogram, meter, and second, like almost all units in the physics that I have learned. Photometry is instead concerned with measuring the brightness of light. My high school only has one physics class, and it doesn't even mention photometry. While I had a great physics teacher, and almost everything in that class was new and interesting, there simply was not enough time to cover even a small piece of physics. I think that schools should radically increase the amount of physics courses available. Physics is an important tool for understanding how the world works. Physics also leads to many inventions. Increasing the number of physics courses would be an investment in the future. I am thankful that the district is investing in the future by sending us to this physics program. I merely wish that  there was more physics available to all. During lunch, Mr. Hillyer came in. Mike and I went with him to meet Mr. Ramsey and the Vanderbilt cohort. Unfortunately, Mr. Ramsey was on the phone, and the other cohort was in an informational meeting. Mike and I then returned to the lecture hall. 

While we waited for class to start, I overheard one of the assistants talk about imaginary numbers and data compression. Evidently, companies have functions that produce complex numbers as a way to send data more efficiently. I found this just fascinating. It connects two of my interests: math and programming. Hopefully, some day I will be able to take a class that delves into this subject. Our teacher lectured on how refraction works. It was extremely interesting. He told us how the physical properties of what light passes through changes how it will reflect or refract. We next did a lab to explore reflection and refraction. We shined lasers through various lenses and shapes, to measure its index refraction and its critical angle.