Dance Showcase (Last Blog!)

Wow, I can't believe that this is the last physics blog for the year! Well, on Friday, we had our spring dance showcase and I realized that a lot of physics concepts were involved. The dancers that did jumps and flips in the air all followed projectile motion and conserved energy as they gained and lost potential and kinetic energy. Our class had to chant and hit our ipus to produce sound waves. We hit our ipus on cushions in order to reduce the impulse of the ipus by increasing the time of contact with the ground so that our ipus wouldn't break. When we spun around in circular motion (with our extremely heavy skirts exerting a force of mg that is always always always downward), our skirts opened outwards because of the fictitious force. There were lots of stage lights that were different colors because they had different wavelengths and frequencies of electromagnetic spectrum. At the end of senior tribute, some seniors were blowing bubbles on stage and I started thinking about how refraction and thin film interference were creating those changing colors. So, there's no more dance for the rest of the year, and physics is going to be over after the ap exam tomorrow...how time flies!

Glasses

I was practically out of ideas for this (second to last?) blog when I realized that my blog topic was right in front of my eyes (literally). Ok, so it's a pretty boring topic, but it goes back to some concept we learned in the optics section. I'm nearsighted, so I wear my glasses (or contacts) to help me see things that are far away. My glasses have diverging lenses, which make objects appear smaller but clearer. The diverging lenses refract light so that the images appear at the retina instead of in front of the retina. People who are farsighted have glasses with converging lenses to make closer objects appear clearer. The converging lenses refract light rays in order to adjust the position of the image so that it appears at the retina instead of behind the retina. Well, I'm definitely going to be using my glasses until late at night everyday this week seeing as there are tests pretty much every day this week...good luck to everyone who's in ap phys, apush, pch, dance showcase, and other exam giving classes this week...

New Air Conditioner

This week we got a new air conditioner installed in our living room. Thanks to the thermodynamics of the air conditioner, our living room is a lot cooler now. The air conditioner uses an adiabatic process to make the air in the room cool without a net heat transfer in the system. The first law of thermodynamics states that Q=W+ΔU. Therefore, in an adiabatic process, since there is no net heat transfer, the work done by the system is equal to the opposite of the change in internal energy. Work is positive, so that means that work is done by the system on the gas. The gas is alternately expanded and contracted to reduce the temperature of the air in the room. Well, the air conditioner will definitely be useful seeing as summer is slowly approacing...which also means that ap exams and the end of this class are near! Only a few more weeks of physics!

Pearl Harbor and Family Fair

Wow, what a great long weekend! Pearl Harbor field trip, Family Fair, and an extra day off from school! And only 4 days of school this week! So at the Arizona Memorial at Pearl Harbor, I, along with many of the other ap physics students, were distracted by the thin film interference pattern on the surface of the water. There was a thin film of oil on top of the water because oil was leaking from the USS Arizona underneath the memorial. I could see the thin film interference pattern because light reflected off both the top and bottom of the thin oil film, creating regions of alternating constructive and destructive interference. The ripples in the water show harmonic wave motion probably created by a disturbance such as the wind/ rain (it was super cold-totally could have used a jacket) or the boats moving in other parts of the harbor. At Family Fair, I felt the imaginary outward force created by the circular motion of the Turbo Tubs. We turned the wheel really fast so that we could move at a high angular velocity. Thus, decreasing our equilibrium and feeling extremely dizzy afterwards... :P. This weekend was filled with a lot of physics and a lot of fun!

The Hiroshima Atomic Bomb

Since we've been learning about nuclear physics, I thought about the atomic bombs dropped on Japan at the end of World War II. When I went to the Hiroshima Peace Memorial over spring break last year, I could see the massive amount of destruction that was caused by the atomic bomb. The first picture is a part of the Hiroshima Peace Memorial, the second is a replica of a slight shadow of a person who was sitting on the steps when the bomb exploded, and the third is a picture of a watch that stopped at the exact time the bomb exploded. It is hard to believe that just one atomic bomb and some microscopic fission reactions can decimate an entire city. Fission occurs when an atom, such as Uranium-235, is bombarded with a neutron to separate the nucleus of the atom into two smaller atoms. Because the strong force attracting protons to each other is broken with the introduction of the neutron, a large amount of energy and more neutrons are released. The released neutrons start more fission reactions and the chain reactions continues, resulting in the massive amount of energy released by an atomic bomb or nuclear power plant. The dropping of the atomic bombs was a negative use of physics in history and hopefully will never be used again.

Waterpark

I went to my friend's birthday party at the waterpark and although I don't believe my friend sent it an invitation, physics definitely showed up! The fact that we were all pretty tanned and/ or sunburned afterwards proved that the ultra-violet part of the electromagnetic spectrum mitigated the practically futile efforts from our sunscreen. Many of the rides were basically slides of different shapes and forms. If gravity didn't exist, we would not accelerate down the slides and we wouldn't feel the thrill! On one particular ride, Raging River (shown above), there were many points at which we felt like the raft was going to fly off of the slide. However, the opposing force of gravity towards the center of the earth always kept us on the slide. We switched groups and I noticed that when we rode with the bigger guys, the raft was even closer to flying off of the slide. This is because the momentum was greater. Momentum=mv and the heavier guys added to the mass in the raft. Therefore, it took gravity longer to change the direction of the raft and we felt like we were going to continue flying off the slide. I guess it was a good thing that physics came otherwise this party would not have been as fun as it was.

Mirror, Mirror, on the Wall...Wait There's More Than One...

When I opened the bathroom cabinet, I realized that the mirror doors created multiple reflections like in one of our labs. When the door opens all the way like in the first picture, the two planar mirrors are perpendicular to each other and they create 3 images. An image is created each time light rays bounce off the object, hit a mirror, and then reflect into my eyes. The images in front of the mirror are real and the images on the opposite side of the mirror from me and the camera are virtual. The virtual images behind the mirrors are the same distance away from the mirrors as my finger is from the mirrors. The virtual images cannot be seen but I could see the real images if I held a piece of paper in the correct place in front of the mirror. When I opened two of the doors at the same time like in the second picture, I saw many, many images because there was an image everytime the object or an image of the object existed in front of a mirror.