Physics
rallain | March 23, 2010I already looked at ESPN's Sport Science episode where they calculate that Marshawn Lynch produces 54,000 watts when pulling some tires. Yes, that is way too high. However, what would happen if some was actually that powerful? What could that person do? How fast could they run 100 meters? That is what I am going to calculate.
First, I am going to assume that Marshawn has a mass of about 100 kg. Also, let me say that he can produce 54,000 watts no matter what his speed.
Take a short time interval. During this time, Marshawn will increase his speed from say v1 to v2 this would be a…
drorzel | March 23, 2010The winners of the first Research Blogging Awards were announced today, and I was very pleasantly surprised to find that this blog was named the "Best Blog -- Chemistry, Physics, or Astronomy." I knew that I was nominated-- I was one of the judges, and while I abstained from voting on my own blog, I did see it in the list with many other excellent blogs. Given that research blogging is only a small part of what I do, I didn't expect to win at all.
(In the manner of such awards, I now feel guilty for not having done any ResearchBlogging posts in ages, so I've queued one up for tomorrow morning…
rallain | March 23, 2010I happened to catch two parts of two different episodes of Meteorite Men - a show about two guys that look for meteorites. In both of the snippets I saw, they were talking about a debris field for a meteor that breaks up. In these fields, the larger chunks of the meteorite are further down in the field. Why is this?
Let me approach this first from a terminal velocity view. This requires a model for air resistance. I will use the following:
Where:
rho is the density of air
A is the cross sectional area of the object
C is a drag coefficient that depends on the shape of the object
v is…
drorzel | March 22, 2010I gave a talk today for a group of local home-school students and parents, on the essential elements of quantum physics. The idea was to give them a sense of what sets quantum mechanics apart from other theories of physics, and why it's a weird and wonderful thing.
The title is, of course, a reference to How to Teach Physics to Your Dog, and the second slide was an embedded version of the Chapter 3 reading. I set the talk up to build toward the double-slit experiment with electrons, using the video of the experiment made by Hitachi. Here's the talk on SlideShare:
What Every Dog Should Know…
esiegel | March 22, 2010Welcome back to The Greatest Story Ever Told, where we're bringing you the story of the Universe. We're going to go from the very beginning -- before the big bang -- up through the present day, and tell you how we got here. This is part seven, and you can always go back for parts 1, 2, 3, 4, 5, and 6. Last time, we got rid of all the antimatter in the Universe by letting it cool enough that every particle-antiparticle pair in the Universe annihilated with one another, producing a huge excess of radiation.
But there was also a little bit of normal matter -- protons, neutrons, and electrons…
rallain | March 22, 2010This is a topic that I am going to talk about in my physical science class. Might as well make a post about it, right?
Here is the deal. You are in a pool. You drop a quarter in the deep end and swim down to get it. I know the first thing you are going to ask: Why do I have a quarter in the pool? Does it matter. What matters is that your ears are killing you. Boy, that hurts. Why do your ears hurt and what can you do about it?
Pressure and depth
When you put a fluid in a gravitational field (like on Earth), the pressure in that fluid (or gas) increases as you go down. Why? There are…
bioephemera | March 19, 2010A slight science journalism FAIL in a story at iO9, originally from the New Scientist:
the Title: "First Quantum Effects Seen in Visible Object"
the Lede: "Does Schrödinger's cat really exist? You bet. The first ever quantum superposition in an object visible to the naked eye has been observed."
the Discovery: "[researchers showed] that a tiny resonating strip of metal - only 60 micrometres long, but big enough to be seen without a microscope - can both oscillate and not oscillate at the same time."
the Wait, what?: "Alas, you couldn't actually see the effect happening, because that very…
esiegel | March 17, 2010I have this one little saying. When things get too heavy just call me helium, the lightest known gas to man. -Jimi Hendrix
Hendrix is almost right: helium is the second lightest gas known to man, behind hydrogen. But there are many applications for helium -- both scientific and non-scientific -- that make it incredibly useful and practical. Helium is far lighter than air and is inert, which means it won't combust when you combine it with air and energy, like Hydrogen does (below).
(Too bad for the kids who want hydrogen balloons for their birthday parties!)
In addition to being lighter than…
rallain | March 16, 2010Pre Reqs: vectors, forces
This is typically the first topic in the second semester of introductory physics - the interaction between objects with electric charge. There are 4 fundamental forces that physics typically looks at:
Gravity - an interaction between objects with mass - wow, I don't have a post on the universal law of gravity?
Electromagnetic - an interaction between objects with electric charge.
Weak Nuclear - an interaction between (let me just say for simplicity) leptons.
Strong Nuclear - an interaction between hadrons.
I know those last two are complicated - but I am not going…
drorzel | March 15, 2010I'm terrible about taking notes on conference talks, especially when I'm jet-lagged and was sleep deprived even before I got on the plane. I do jot down the occasional paper reference, though, so here are the things I wrote down, and the talks they were associated with. This should give you some vague idea of what the meeting was like on Monday.
From Joel Moore's talk on topological insulators, one of the Hot New Topics in condensed matter, a review in Nature.
From Phillip Treutlein's talk on optomechanics, a recent preprint on coupling atoms to mechanical oscillators.
From Nathaniel Brahms'…
esiegel | March 15, 2010Bart: Go, Dad, go!
Lisa: How doth the hero, strong and brave, a celestial path to the heavens paved!
(The family stares at her.)
Lisa (dejected): Go, Dad, go. -The Simpsons
Last week, I got a question from one of my online friends, cmgraves. His question was straightforward:
How do thrusters work in space? On Earth, when we want to speed up, slow down, change our direction, or to change our motion in general, we always have something to push against. This is true whether you're a runner and have the ground to push against,
or a turbofan engine with the air to push against.
But in the…
esiegel | March 12, 2010Earlier this week, I wrote about an inclined treadmill, and talked about physical work. Physically, the amount of work that you do is equal to the amount of force that you exert in a certain direction multiplied by the distance you move in that direction.
If you walk up an incline, as opposed to moving on a level surface, you have to also fight the force of gravity to get up that hill, hence you have to do extra work.
I contended that, in order to walk up an inclined treadmill, you also have to do extra physical work, the same way you have to do extra physical work to walk up a real hill.
"…
pontiff | March 12, 2010The APS March meeting is next week as 10000 physicists invade Portland, Oregon. I hope Powell's bookstore has stocked their science sections well! GQI, the topical group on quantum information, sponsors a good number of sessions at the meeting including sessions with invited talks, focus sessions, and general sessions. Below the fold I'm assembling a list of quantum computing sessions, but before the fold I'd like to point out the invited sessions, which have longer speaking slots where one can actually learn more than the speakers name and research project title, that are sponsored or…
pontiff | March 11, 2010Hm, today we seem to have a posting from beyond the grave, arXiv:1003.2133:
Proof of the Ergodic Theorem and the H-Theorem in Quantum Mechanics
Authors: John von Neumann
Abstract: It is shown how to resolve the apparent contradiction between the macroscopic approach of phase space and the validity of the uncertainty relations. The main notions of statistical mechanics are re-interpreted in a quantum-mechanical way, the ergodic theorem and the H-theorem are formulated and proven (without "assumptions of disorder"), followed by a discussion of the physical meaning of the mathematical conditions…
pontiff | March 11, 2010A theoretical condensed matter postdoc of interest to the quantum computing folks:
Postdoctoral Research Fellow in Theoretical Condensed Matter and Quantum Information Science at the Laboratory for Physical Sciences, University of Maryland.
Applications are being accepted for physics postdoctoral research positions in quantum information and device theory at the Laboratory for Physical Sciences (LPS) at the University of Maryland-College Park. Demonstrated expertise in one or more of the following categories is desired: semiconductor/condensed-matter physics, solid-state quantum computing (e…
pontiff | March 11, 2010Ever wanted to ask a Nobel Laureate in physics a question? Well here's your chance: check out this youtube page where you can upload your own questions to Albert Fert, 2007 Nobel prize winner for Giant Magnetoresistance.
drorzel | March 11, 2010Lots of good suggestions as to Portland activities for my trip to the March Meeting next week. There's a second, related problem that I also need help with: What should I do at the meeting itself?
My usual conference is DAMOP, which I'll be going to in May, so while DAMOP is a participating division, and offers some cool-sounding sessions, it seems a little silly to go to the March Meeting and go to DAMOP talks. The whole point of being at the gigantic meeting is to see different stuff than usual.
The problem is, the scientific program includes forty-odd parallel sessions in each time slot,…
esiegel | March 10, 2010A bad day for your ego is a great day for your soul. -Jillian Michaels
One of the most popular exercises at the gym is the treadmill. And why wouldn't it be? Whether you're running or walking, it's a great way to get your heart rate up, get your body moving, and for many people, a great way to burn calories.
But however you use a treadmill, there's one extremely simple thing you can do to dramatically intensify your workout: incline it!
If you're an outdoor walker/runner, this is the equivalent of going uphill instead of over level ground. There are many physiological differences in walking…
drorzel | March 9, 2010I'm going to be attending the March Meeting of the American Physical Society next week, in Portland, OR. This will be held at the Oregon Convention Center, which is apparently on the opposite side of the river from every hotel in the city.
I have never been to Portland (or, indeed, anything in the Pacific Northwest) before, so I have no idea what there is to do there. I'm sure that at least some of my readers have been there or are from there, though, so here's your chance to clue me in: What essential Portland activities/ eateries/ whatever should I make sure not to miss while I'm there?
I…
esiegel | March 8, 2010Electricity is actually made up of extremely tiny particles called electrons that you cannot see with the naked eye unless you have been drinking. -Dave Barry
Welcome back to our series on The Greatest Story Every Told, where we start from before the big bang and come forward in time to get the Universe we have today. (If you're just joining us, go back for parts 1, 2, 3, 4 and 5.) Last time, we talked about how we made more matter than antimatter (and we clarified some questions). So what does our Universe look like at this point?
Well, the Universe is still full of hot radiation, flying…