Interesting Definition and 754 Threads

Little Tyke [my office cat] came into the office and started making a lot of noise knocking about. Then I realized why: She had brought in a snake that was close to a four-feet long! Cripes! After fighting to keep her away and finally managing to catch the snake by grabbing the tail, as I was...

Found this on the door to a bathroom stall at work. I thought it was interesting to see a literary reference in a graffito. Perhaps "Screwtape" has some other significance to the author other than the book by C.S. Lewis though. Does anyone else have interesting graffiti to share?

I'm a normal adult male (abt 6ft tall, 180 pounds), if my density was that of the mean density of the universe, what would be my volume?

What area of Electrical Engineering is most interesting with respect to research/specialization? I heard from somewhere it's Telecommunication. any suggestions?

Very Interesting Question on Division of Polynomials! [b]1. Question: 'When a polynomial f(x)= x^4 - 6x^3 + 16x^2 - 25x + 10 is divided by another polynomiall g(x)= x^2 - 2x + k, the remainder is x+a. Find the value of a k and a'. Homework Equations [b]3. I tried solving it by...

I caught this in the NY Times: http://community.nytimes.com/comments/www.nytimes.com/2009/06/28/health/research/28cancer.html?sort=oldest&offset=4 The article focuses on cancer research, but the conclusions can be applied to all medical research. As the article correctly pointed out...

Tom.stoer recently started a thread to collect ideas on the topic of stringy dislike of LQG. I thought that was a constructive initiative. At least for me it was helpful to sample what are the current rationales of dismissal, in part because this is a kind of folklore that has changed over time...

Homework Statement Let U be a fixed nxn matrix, and consider the operator T:Msub(n,n)---->Msub(n,n) given by T(A)=UA (look familiar?:biggrin:) Show that if dim[Esub(c)(U)]=d then dim[Esub(c)(T)]=nd. Homework Equations The Attempt at a Solution The author provided a small hint. He suggested...

Hello, again! I got one very interesting question. We got three archers, and the probability of the ones to hit the target is: A1, A2, A3. What if the task is to find the probability that the target will be hit at least from one archer. So at least one archer to hit the target. Is it P(A1 U...

What will be the most interesting improvement in technology? I like to read up on new advances in science and often read about fantastic predictions in science. For example, in the world of television: http://www.sciencedaily.com/releases/2008/10/081002084217.htm"...

Homework Statement You ask your friend if the football is on 9pm or 10pm. He sometimes tells the truth and sometimes doesn't. What should you ask him so that you will be certain which time the football will be on? The Attempt at a Solution ASK: Is it true that 'You are telling the truth...

I enjoy learning new things every time I do a problem set. Take the wheatstone bridge for example. Upon my initial observation, I concluded that the total upper electric potential(V1 + V2) minus the lower electric potential(V3 + V4) ought to give the electric potential that exists across the...

I have to do a presentation on atomic theory and periodic table. What are the interesting points I can include to my presentation? Thanks in advance!

Homework Statement This week’s physics puzzle is a classic often used in mechanics. A point-like marble of mass m is situated on top of an immobile hemisphere of radius R. It is given a tiny push and starts rolling down. At what angle θ will it detach from the hemisphere’s surface and fly...

Allright call me a naturalist , for those of you interested I had a short encounter with mother nature the other day. Friday afternoon - I found a starling bird in my front lawn , it was being real still with its head pointed to the sky. It started to hop in the other direction as soon as it...

Peugeot have a new hybrid 4x4 They took a regular front wheel drive car and added an electric motor driving the rear wheels only. It can run ICE + front wheel only for freeways without the extra drag of permanent 4wd Electric rear wheel only for in-town/traffic low speed, or Diesel front +...

We are to find a scientific argument and either prove it or debunk it through research. This was an introductory Physics class and he would prefer to stay somewhat within the scope of the class. Does anybody have interesting debunk-ings?

Homework Statement Evaluate the integral, (x^2+3x-8/x^2+16)dx, without using partial fraction expansion. Now this has really confused me. I know that partial fraction expansion is not viable because the mumerator has a higher power overall than the denominator The Attempt at a Solution...

Hi, first I want to apologize for my english. I'm not from an English speaking country and I have to practise. I have a quite interesting physical assignment for you. I was trying but I still can't solve it. If you would have an idea or if you would know how to solve it please let me...

Homework Statement There Are two bodies with mases M1 and M2 placed in space separated by a distance D. They attract each other due to gravitational forces and hence acclerate towards each other.The problem is to Find out the time taken before their collision? Homework Equations I know...

I have spent a long time stuggling with an interesting problem which was set up by my brother some time ago: Consider an object that starts moving along the line according to the equation below: v(s)=1+{s}^{2} where s is the total distance traveled by the object and v is the velocity of the...

Some of you may have heard this before, but its one of those classic problem that I love debating, so please weigh in if you think you have the answer... You have an S-shaped sprinkler, when water is run out of it the sprinkler rotates about its center axis in the opposite direction to the...

There is a cunducting hollow sphere. We know if we charge it all the charges will stay at the outer surface. But if we drill a hole of radius r(say) then what fraction of the charge will remain inside and outside surface I think it is logical to think that less charge will stay in the...

Hi all, I have a presentation for my engineering-based public speaking class coming up. It must be technical in nature. I can't decide what would be easy enough for me to learn about while keeping it at a technical level and still interesting to my peers. I've been thinking about: A...

p is probability that a man will success in a single shot n is number of shots man is going to make 1)what is probability that a man will score at least one series of at least k successive successful shots (in the interval of n)? 2)what is probability that a difference between his...

i need help finding the limits above and below the branch cut segment of sqrt(z^2-1) for -1<x<1 I always get total phase above is pi/2 and total phase below is 3pi/2 but this is wrong please help

For everyone who watches dirty jobs (I'm guessing most of us) and everybody who works in an industry with health and safety policies (a lot of us). http://www.ted.com/index.php/talks/mike_rowe_celebrates_dirty_jobs.html I hadn't appreciated what a smart and interesting guy the presenter is

Hi all, I have a project to do for system of ordinal differential equations and their applications in physics. One of my tasks is to find where in physics the following system of ordinal differential equations appear: dA1(x)/dx=f(x).A2(x) dA2(x)/dx=f(x).A1(x)+ h(x).A2(x)+ g(x).A3(x)...

I found this on the web, it was written by someone without formal physics education but I was wondering what some educated users here with a background in physics think about it. My problem with it is that he claims time doesn't exist in any perspective only this physical continuity but how can...

I found an interesting rock in a river bed in Arizona once. I think this rock would prove that the Earth is much more than 10,000 years old as creationists like to believe. It was a piece of conglomerate. It had been rounded in the river bed, about 10" across. The interesting thing was that it...

So I had a student today ask me if I could come up with a simple 2 dimensional area problem. I was like -sure what is it. The question was: If a cow were strapped to a tether outside a 10' by 10' square barn, at the corner of a small outlet door, and had a 100' leash/tether, what would the...

Hello All, Was thinking about some of the basic concepts of magnetic induction, in the case of a stationary solenoid coil with a moving magnet crossing the face of the coil. We know that when the magnet approaches the face of the coil and the field increases, that a votlage potential (emf) is...

I have absolutely no physics experience but decided to take Physics C next year as a junior. Is this a good idea? I am a very math-oriented person and the questions that some people as on these forums interest me a lot. So, is physics really interesting? Or should i not take Physics C?

Hello all, I'm in the process of working on developing a course to prepare students for calculus. The emphasis is to build up students' conceptual mathematical thinking, particularly that related to the notion of the function. Recognizing that motivation is one of the biggest issues to...

Hi, I'm presenting a proof that e is transcendental, but I want to spice up the presentation a bit by exploring some interesting perspectives, such as connections to topology, abstract algebra etc. I've already selected the Lindemann–Weierstrass theorem as a possible candidate. Can you suggest...

Homework Statement Two satellites are launched at a distance R from a planet of negligible radius. (Yes, that's what the problem says...) Both satellites are launched in the tangential direction. the first satellite launches correctly at a speed v_0 and enters a circular orbit. The second...

"Think of what you're saying, you can get it wrong and still think that it's all right." from some song by John Lennon and Paul McCartney. anyway, this got me thinking about how many times I've though I've really understood something, or was absolutely sure that I was correct about...

I am picking courses for next semester and am torn between a numerical analysis class or one on Fourier series and wavelets. The n.a. course fits my schedule way better but every book and syllabus I have browsed concerning numerical analysis has seemed uninteresting--more like a branch of CS...

I've ecountered three interesting problems lately: 1. On a motionless sphere you can lay a cylinder. In what conndtions it is possible? After we move cylinder by a little degree it starts to vibrate and after a short period of time it goes back to the static situation. Why? 2. When mooring...

Apparently students were given an assignment to prove whether hell obeyed the laws of thermodynamics and if it was endothermic or exothermic. The most interesting response is given below. http://wfhummel.cnchost.com/hell.html author unkown.

I am trying to make a function which is exponential for a while, and then turns gaussian: f(l,d) = \lambda e^{-\lambda d} , 0 < d < l and f(l,d) = (1-\int_0^l \lambda e^{-\lambda d} dd) \frac{1}{\sigma \sqrt{2 \pi}} e^{-(d-l)^2/(2\sigma^2)} , l < d < \infty (That is supposed to be...

Hello here you have the same question in the enclosed What is the average value? average value for (exp \alphaZ ) = \int\int exp\alphaZ ds / \int\int ds Over the sphere S: X^2+Y^2+Z^2=a^2 Also by use the parameterization X= a sinϴ cos ɸ Y= a sinϴ sin ɸ Z= a cos ϴ...

So next semester I am studying one section of the Philosophy of Physics at Oxford. This is paid for through my college; thus I can only take 9-12 hours (I am going the third term which doesn't start until late April). I am already a little behind because I had trouble deciding and have three...

What do you think is some interesting or/and sensible way to define functions like exp(), cos() provided basic algebra rules (including integration) are known? I make a suggestion I came up with \ln x:=\int_1^x \frac{\mathrm{d}t}{t} from where key properties follow directly. For example \ln...

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Hi guys, I've been dropped in at the deep end at work, tasked with designing a latching mechanism for an armrest on a luxury aircraft seat - It has to work on a remote latch principle, ie by pushing a sprung-loaded button downwards to actuate a link arm via a pivot, which then retracts the...

I was having a debate with a friend about how to show the following limit. \lim_{n \to \infty} \cos( \frac{2 \pi}{2n - 2} )^n = 1 I claim that you can just hand-wavingly say that since cosine of 0 is 1, and 1^infinity is 1, the limit is 1. He claims I need to show this using some sort of...

Heres something i came across in a book but there's no solution... take two inspectors in a factory (they can't talk to each other), and they inspect a series of products and they deem them defective or not. So the results would be (D,N), (N,N) ... where each coordinate is each inpectors...

I went to the Uni of Birmingham open day this weekend gone, with the intention of finding more about both the Physics and the Mechanical Engineering degree programmes. Firstly, the Mechanical Engineering talk was disappointing. Mostly because the guy giving it was a bit of a dick. All he...

Hey everyone, I was given this fun little probability question from my tutor after I finished early in one of my classes about three weeks back, and I just can't seem to crack it! Something about gambling and probability makes my brain go haywire (or maybe its some other, deeper problem...