Physics Class Review

This is my last post on the blog as our 6 weeks of Summer Physics comes to an end. It's been a great 6 weeks and although we covered so much material, I really felt like I grasped the concepts. I had always thought that Physics was just another science course that you had to get over with in order to graduate, but now I understand that Physics is the course that connects classroom science to real-world science. Science was never my forte so I always had a mental block about science courses, but I think Physics really opened my mind up to science, as I really enjoyed the course. In this class, I learned that Physics is actually around us everyday, as it is one of the few science courses that are applicable in our daily lives. The thing I liked about this course was that it was applicable outside of the classroom. Our sophomore science course, Chemistry is structured around lab-based learning and was confined in the four walls in which it was taught. Yet Physics allowed me to apply what I learned that day in class to what I saw around my house or outside. The learning didn’t stop after class was over as I could connect objects around me back to the unit we were learning. But something that could be modified to improve the class was the speed of learning. I found the first semester to be fairly easy, as the learning was spaced out so the pace of information we needed to absorb was very manageable. Yet as we started to move into the second semester, the pace of the class sped up dramatically and it was much more challenging to keep up with the pace of learning and information that was thrown at us. The tests got harder and I think everyone in the class would agree that the second semester was way harder than the first. On the other hand, because Physics is a cumulative course, it was expected that the further into the course we got, the harder it would become.

Unit 10 day 3

Today in class we went into depth about refraction and reflection. We were shown multiple demos that helped us to understand how light is affected when moving between mediums of different "speeds". For example, when light passes through air into water, the reflection will be bent because air is a faster medium compared to water. At first this was really confusing and mind boggling, but after practicing these concepts through worksheets and Once I got home, as I was drinking a glass of water, I decided to use a straw to apply what I had learned in class today. As you can see from the picture below, the straw looks like it is bent, yet common sense tells us its not. Because air is a faster medium compared to water, the ray of light (that allows us to see the straw) bends closer to the normal, perpendicular path of light. Because of this, the straw looks bent when it is really intact.

Unit 10 cont.

Today in class we learned in more depth about electromagnetic waves. Mr. Blake did a really cool demonstration with light pigments, showing us how the colors interact with each other as we explored all the different color combinations. At first, we only explored the mixture of primary colors (red, green, blue) and their product of secondary colors (cyan, magenta, yellow). Then we delved into the concepts of white and black, which is the presence of all colors and the absence of all colors. This made me think about kaleidoscopes. They only work if you aim them at light. There are many multi-colored chips of glass/plastic inside that swim around in the prism. The combinations of colors and the angled reflection of the light causes the infinite colors and patterns within the kaleidoscope. Seeing Mr. Blake's color demonstration today really got me thinking about the complexity of our childhood toy. 

Unit 10

Today in class we started our last unit on electromagnetic waves and light. We learned the fundamental concepts about light, and we put into perspective the speed of light. I was amazed to learn that sound can travel 3.5 football fields per second, while light can travel 3 million football fields per second. I knew light travelled a lot faster than sound, but I never knew how much faster. Another aspect of light we focused on was the transparency of it. There are three levels of transparency. There is opaque (where no visible light can pass through it), translucent (where some visible light can pass through it) and transparent (where visible light can fully pass through). Once I started thinking about these three terms, I wondered if there were things that had multiple transparencies in one object. It turned out it was very common. One example is a clock; the surface of a clock is totally transparent so you can see the numbers behind it. Yet the second layer of a clock is opaque – if the second layer weren’t opaque, it would be very hard to read the time, as all the mechanisms of the clock would be visible. This made me think about how the functionality of many objects depends on what transparency the material has.

Unit 9 cont.

Today in class we started to learn about sound and the interaction between waves. On Thursday (yesterday), we talked about constructive and destructive interference, but today we learned about interaction between waves in a more visual way. We graphed the motion of waves for each second until the two waves had interacted and passed each other. When I was at the Kaupiko regatta this weekend, I sat on the beach with my crew, watching the waves. This got me thinking about physics. You could clearly see the waves breaking far off shore, and sometimes the waves would crash together and create a huge splash. Other times, one wave would surrender to the other and would go under, creating no turbulence above the water at all. Likely, when motion or sound waves have destructive interference, the waves would cancel each other out, resulting in a flat line. On the other hand, when motion or sound waves have constructive interference, the resulting wave would be larger than either of the original waves.

Unit 9

Today, in class we spent a lot of time on a spring lab where we explored the concept and physics aspect of waves. We got a long slinky and three weights, and lined up the weights at incremental distances from us, parallel to the slinky. We learned how to create constructive and destructive interferences by adjusting how hard we whipped the slinky, how much we swung the slinky, and how often we waved the slinky around. By adjusting all these parameters, we were able to control which weight the slinky would hit. Playing around with the slinky reminded me the gongs that were popular in Buddhist temples back in Japan. Every New Year, it was a Japanese family tradition to go the temples to pay our respects and to make a New Year's wish by hitting the gong, clapping two times and bowing your head as you made your wish/prayer. If and when you hit the gong super hard, your hand often vibrates and shakes even after you hit the gong. Doing the slinky lab in class, it made me realize that it was because the waves of vibration still carry through your hand (a solid medium) that you felt the waves of motion transferred from the gong to you through your hand.

Water Bottle Rocket Summary/Reflection

For our rocket, we cut the top off of a 2-liter soda bottle and attached it to the bottom of a second, complete bottle. We at first added cardboard fins to help the aerodynamic aspect of the launch and 20g weights to the bottom of our rocket to ensure that it would fly with the parachute on top. Yet after multiple trials, the cardboard fins started getting beat up and flimsy and the weights on the bottom were causing the rocket to fall too fast through the air. Therefore we ended up taking both design features off. For our parachute, we had two designs. The first design had slits to create the four corners of the parachute and we made loops at the end in which to attach the parachute to the rocket using thin rope. Once fully expanded, this parachute looked similar to a grocery shopping bag flying through the air. (with handles) The second design was a double-layered square with the four corners tied down to the bottle. Though we used the first design for all of our practice launches, when it came to launch day we ended up liking the square parachute a lot better. We then capped the rocket with a cone at the launch, which helped with the aero dynamicity of it and once it started to descend, the cone flew off and the parachute deployed. 

On launch day, we quickly discovered the endless list of things that could go wrong with each launch. Many times our rocket would fly super high but then the cone would get stuck on the bottle and the parachute wouldn’t deploy. At other times, we had too much or too little water so the amount of fuel wasn’t right. At other times, the pump would be really tight so it was hard to get the right air pressure and so when we were tired we would just give up and launch it. And sometimes, water would leak from the stopper and the rocket wouldn’t launch as high. As you can see, many things can go wrong with each launch so it was very frustrating to try and get everything just right.

By doing this lab, I learned about aerodynamic design and structures. Trying to make our rocket as aerodynamic as possible, we tweaked our structure many times. This got me thinking about aerodynamic structures in real life such as bullet trains. Because I am thinking of it in a physics manner, I realize now that bullet train's structure are designed for its aero dynamicity, as the nose can cut through air and walls are smooth, with nothing that will add air resistance.