# willorn

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1. ## College

Quite well. I've enjoyed myself and my classes here. The course Modern Physics has just been removed from the curricula and sort of integrated into Quantum Physics I so I'll be taking that next semester. Yeehaw!
2. ## College

[ATTACH=CONFIG]371[/ATTACH] We don't always work in the library. Maybe this thread could be about college and high school seniors could ask questions. I know I had a lot when I was taking AP C.
3. ## College

I'm in it. Professors are awesome. I was reminded of Aplusphysics and a certain professor when I caught up to the Big Bang Theory episodes a few days ago. Honors Physics seems to be starting slow but I hear tales that it will kick my butt. More to follow.
4. ## Challenge problem, week of 11/29/10, Part II

A quick re-work of my work yeilded a much stranger looking answer, but since I could find no fault in my original method, I can only assume my new answer to be the simplest form solution. (Sidenote: the "IK" term towards the end should be positive after it is added to both sides, I got caught up in Latex)
5. ## Physics in Billiards

Oh darn, they stopped working again
6. ## Musing

I can already tell this post will have a lot less structure than usual. I've been thinking about special relativity quite a bit more than usual these past few days, in particular, the twins paradox. We didn't discuss it, but it seems to me that the actual aging is not the paradox involved, but the question of which twin aged how much is the paradox, since the earth twin would believe the other twin to be 40 years older and the space twin would think himself only 4 years older. Secondly, we discussed that special relativity applied to objects either in constant motion or at rest. In other words, objects in an inertial frame of reference. That being said, the brother traveling in the spaceship must have experienced some sort of acceleration throughout his journey, when he left earth for example, and most likely when he turned around and when returned to earth. Therefore, I do not even think that the laws of special relativity apply to this situation. The question then for me is in that situation what would happen? I imagine that the twin on earth has aged physically by forty years and that the twin who traveled has aged physically by just four years, and that no paradox exists at all. Something else I have been thinking about: E=MC^2 I never truly understood the principle, so I looked online for the experiment used to determine this formula, and then attempted to derive it myself. I found that a useful experiment to reference (although theoretical) is this: a box is stationary in a vaccuum. A photon moves through the box from left to right. Since a photon technically has momentum, the box must then move left in order to conserve momentum of the system. When the photon reaches the right side of the box, the impact causes the box to stop moving. However, since no external forces acted on the box, its center of mass must be in the same position as before (new concept for me!) but the box has moved left. Therefore, Einstein determined the photon must have a mass equivalent in order to satisfy the laws of physics. I dreged up an equatin devised by Einstien to get started. I wonder if he came up with this expression before or after he determined that E=mC^2, because that would make this post seem rather silly. Since, a photon is massless, I was able to draw a simpler conclusion from his equation.The momentum rho is the momentum of both the box and the photon, by conservation of momentum. Running low on ideas, I nosed around some more, and found that I should start thinking about the time it takes the photon to move from side to side. That train of thought led me to the following. The key is that velocity is change in displacement over time and that the time the photon required to cross the box is the length of the box side over the photon's velocity. Thanks to what I learned this year in class, I know the center of mass of a system can be expressed the sums of products of mass and displacement of all individual parts over the sum of all individual masses. I determined that if the center of mass did not move, then the position of the center of mass must have been in the same position as the box after the system resolves itself. We can substitute X2 (the displacement of the photon) to be L the length of the box because it traveled the full length of the box. Reviving the previous equation created and substituting it for m(delta x): (I can do this because although the expression reads differently, the displacement after represents the displacement of the photon after colliding with the box's side, and the Mass is of the same object in both cases) I find that deriving an equation always helps me to conceptualize it, and I hope this derivation helps you too! In my probing I also discovered that all mass has a measurable frequency, although it has little or no effect on people. More on that later...
7. ## Australian Intern makes major discovery in the Field of Astrophysics!

http://www.brimbankweekly.com.au/news/national/national/general/student-helps-solve-cosmic-mystery/2176857.aspx?storypage=2a http://news.yahoo.com/s/afp/20110527/sc_afp/australiaastrophysicsscience This audacious undergrad made a major discovery while on break! Just goes to show the success teams of scientists can have with a fresh perspective. For a background of the "Missing Matter" Problem, try wikipedia: http://en.wikipedia.org/wiki/Dark_matter#Observational_evidence
8. ## Switzerlands super Collider: The Large Hadron Collider

If you're interested in Higgs Bosons and hypothetical missing matter, check out my blog/collection of links about the australian undergraduate student who made a groundbreaking discovery in the field of particle physics!

Fascinating!
10. ## Challenge problem, week of 11/29/10, Part II

I used the same method as for part I but with Kinetic Energy having both rotational and linear components. I have begun the derivation using some geometric observations made in Part I of the problem. *note: this derivation will be hard to follow without first walking through the solution to Part I of the challenge problem. Finding the changed velocity: (This time around, I figured the kinetic energy at the time the ball leaves the basketball would have both rotational and linear kinetic energy because it is rolling)\ Eventually I changed omega, rotational velocity, into a linear expression to solve for velocity. Just like part I, substitute the velocity squared expression into the cosine expression. recalling the alternate expression from Part I, and recalling that the vertical height "h" is the vertical height "r" After isolating the "k" terms, I had found a solution.
11. ## Challenge problem, week of 5/16/10

I've heard of this phenomenon before, and I believe that once she begins turning, she robs the earth of some miniscule angular momentum, and when she stops turning, the earth regains this momentum. I wish I had a technical explanation.
12. ## Challenge problem, week of 11/29/10

After the conclusion of my AP tests, I think I've finally found a nice solution to this problem! I will employ the wonderful Latex to derive my answer! I began with an FBD diagram, just like my momma (Cermak) taught me. [ATTACH=CONFIG]131[/ATTACH] I began by examining my FBD and drawing trigonometric conclusions. (After receiving word from Frach, I realized I neglected to mention the Normal; It is important to note that the Normal would necessarily be zero for the puck to fly off the basketball, and that the normal force is a function of the centripetal force and therefore: [ATTACH=CONFIG]132[/ATTACH] Then I used my given knowledge that the basketball is frictionless in order to determine that the total energy is conserved in the basketball puck system. [ATTACH=CONFIG]133[/ATTACH] Later of course, I realized I had unnecessarily taken the square root of velocity, oh well. I substitute the centripetal acceleration from the first eqution with its representative expression and substitute my new velocity! At this time I am very hopeful. [ATTACH=CONFIG]135[/ATTACH] And now I am stuck. But here comes the part that took some more observation, if we look at the FBD again, it can be seen that an equivalent theta exists accidentally in the very diagram I just drew! This comes as a result of the basic geometric concept of Alternate Interior Angles. The length that was previously ignored can be expressed as the difference between R, (the total radius) and "k" (the height at which the puck leaves the basketball). [ATTACH=CONFIG]136[/ATTACH] Using a new expression of the same angle theta, I can now set up and solve for what seems to be an answer that is either perfect or too good to be true. Note that I was able to substitute the "h" for "k" in the expression because k represents the vertical height the puck has fallen.
13. ## Super Duper Conductivity

Superconductivity was first discovered by Dutchman and physicist Heike Kamerlingh Onnes, when Liquid Mercury was cooled to just 4.2 Kelvins!! (Using some very expensive Liquid Helium) While measuring the resistance of the substance, Onnes found that at this specific temperature, the resistivity of the substance quite literally dropped down to nothing. Zero Ohms. But whats the significance? Firstly, Onnes had discovered a material that would produce no heat when an electrical current flowed through it, which has huge technical implications. It is being discussed, for instance, whether superconductors can be used to levitate trains (the Japanese are researching a system called MagLev) or transmit power more effectively. Lesser known applications include more effective Magnetic Resonance Imaging (MRI's), more detailed SQUIDS (magnetic field sensors with a variety of applications, namely detecting brain activity), or even to shrink computers down by using smaller wires! What's more, a fascinating phenomenon coined the Meissner Effect goes into action whenever a magnet approaches the superconductor. [ATTACH=CONFIG]127[/ATTACH]The superconductor literally "mirrors" the approaching magnet. For example, if a north pole approaches the material, an identical north pole will be created in the superconductor, allowing the magnet to levitate at a careful height. A more detailed description of this effect derives from essential Electromagnetic concepts, namely the popular Lenz's Law. In a conductor, free moving electrons are always present. When a changing electric field is introduced to a conductor, these electrons seek to flow such that they perfectly cancel any changing field strengths. Unfortunately for the electrons, a great deal of resistance is present in most conductors, which prevents the flow of the electrons from canceling the change in magnetic flux. Thus, we become familiarized with a Lenz's law that provides usually only minimal resistance to flux change. Now the crazy physics begins. In a superconductor, a substance that has negligible resistance, these electrons are able to flow in such a manner that the changing magnetic field is completely canceled! Result: Floating magnets. Whats more, is that the magnetic field doesn't need to be changing for the Meissner effect to go into action! For this reason, the Meissner effect is different than normal diamagnetism (a term that refers to conductors that follow Lenz's Law). [ATTACH=CONFIG]126[/ATTACH] Holy Floating Magnets, Batman! This is an example of a sample cooled with liquid nitrogen, with a cubical magnet suspended above the superconductive material. You may have noticed the thin layer of mist above the conductor; this mist is actually condensed oxygen! This oxygen jumps up to the magnet when it gets too close and quickly evaporates. This is because oxygen becomes liquid at warmer temperatures than liquid nitrogen, and also because oxygen is naturally "paramagnetic" meaning its molecules are attracted to magnetic fields a just a little bit more powerfully than other elements. Superconductors, however, have a long way to go before they become reasonable. Numerous limitations exist. The hottest a superconductor has ever been is 138 Kelvin. The greatest challenge scientists face is getting the near perfect conditions of the laboratory into a household setting. But the future is coming! Its coming fast.

Can't wait!
15. ## Vacuum may have friction after all!

Flabbergasted is the best word to describe my reaction to this.
16. ## MacGyver knows his E and M

The following is a piece of an episode of MacGyver, complete with a FizziksGuy voiceover explaining a fascinating effect of physical stress of ferro materials, called the "Inverse Magnetostrictive Effect" or "Villari Effect." Although understanding this process requires very abstract thought, I highly recommend it for those of you planning to pursue E + M further into the future. It is a fascinating subject! Its important to understand that the process you saw MacGyver use does not necessarily form magnets for all conveniently placed metal rods. MacGyver must have found himself a nearly pure rod of Iron; it is important to also understand that Iron has some RIDICULOUS reactions to magnetic fields and has very particular properties. What this means is that banging metal on your driveway does not a magnet make. In fact, Nickel's tendency to magnetize significantly decreases under physical stress! Isn't that Iron-ic? What this means is that the actual atomic structures of individual metals determine their reaction to stress (that one goes out to all you chemistry dudes). In all my digging, it seems that Magnetostrictive material science is becoming outdated, but I gained some very valuable insight into how my Piezo Electric Violin Pickup works, the processes are not so different. On a side note, the JWST has finally moved into Phase C (Final Design and Fabrication) and although NASA has begun hammering out strict budget rearrangements, the JWST remains on schedule!
17. ## DannyBoy132's Blog Posts

There seems to be some problem with a certain user's blog posts and being able to view them via aplusphysics so here is a direct link to DannyBoy132's first Blog! http://www.aplusphysics.com/forums/blog.php?16-Santa-Claus-is-REAL!!! It's really good stuff.
18. ## Formulas!

Everyone do yourselves a favor and rate this blog like its a five star hotel. It will be easier to find at the end of the year when we've created a million blogs
19. ## Superbowl

You forgot all about the reduced momentum without the added mass of Woodson and Driver in play. On a more serious note, the friction coefficient between players cleats and the turf can be a big deal if a team isn't well equipped and has actually cost teams many a rushing yard.
20. ## Formulas!

maybe I'm jumping the gun but what about good 'ol QVC?
21. ## James Webb Space Telescope

NASA is currently developing a telescope to further probe the final frontier, and this new telescope, called the Webb telescope (after NASA's second administrator James Webb) or JWST, is being launched in many ways to replace the Hubble. It is designed to capture and analyze infrared light and has a primary mirror at least two and a half times larger than the original Hubble, and it is hoped that the Webb will be able to see deep into dust clouds and observe the formation of stars, planets and relay pictures of some of the universes' earliest stars. The possibilities presented are enormous, and unfortunately, the costs have been too. Regardless, Webb is scheduled to be launched sometime in 2014 and promises to be Hubble's finest successor to date. On the telescope's website are some nifty graphic tools that help contrast the Hubble and the Webb. http://www.jwst.nasa.gov/comparison.html The telescope will be orbiting one of only five "Lagrange" points, nearby our planet, which effectively allow 3 masses (the sun, the earth and the Webb are the gravitational forces in question) to orbit each other while staying in the same places, relative to each other. The advantages this gives the telescope are many, including more efficient communication. On top of it all, the Webb looks just like a Star Destroyer. How cool is that? The Webb is still in testing phase, and much of it has yet to be built, such as the large lower structure, which serves to shield the apparatus from eventually harmful rays from the sun. Because the JWST's mirrors are made of beryllium--which serves its purpose beautifully in the low, low temperatures of space--this "heat shield" is needed. To give you an idea of the massive efforts being poured into this project, a huge cryogenic test chamber (a container as cold as space) was created just to test the effectiveness of the mirror, and outfitted with giant magnets that exactly and constantly counteract gravity. No doubt, the Webb will make a splash when it is fully functional, so stay tuned!
22. ## Midterm AP C

After doing very well on the multiple choice portion of the physics exam, I walked into the Part II questions a lot less prepared than I thought I would be. What was encouraging, though, was that even with these difficult free responses (difficult for me, personally) I feel that I could answer all of those problems perfectly if they appeared on the AP exam. Although I forgot much of what I would have needed to know on the part II (the problems were familiar but I couldn't quite get them), I'm feeling very confident that if I do what I can, I can get at least a four on the AP C exam
23. ## SHM in everyday life

I know what you mean. especially with the word thing.
24. ## Challenge problem, week of 11/29/10

Wait just a minute, this outward acceleration doesn't have anything to do with the "centrifugal force" does it?
25. ## Physics Troll

so then, if you did push the stick, a compression would form and move along down the stick until it finally reached the end and the stick returned to its former length