Interesting Definition and 754 Threads

I was going to read the whole thing but it was a long article http://en.wikisource.org/wiki/Industrial_Society_and_Its_Future#The_.27bad.27_parts_of_technology_cannot_be_separated_from_the_.27good.27_parts Do you think much of what he said was true?

An interesting inequality--question on the proof... I am working on the following proof and have gotten about half way; If a_1, a_2, \ldots , a_n are positive real numbers then \sqrt[n]{a_1 \cdots a_n} \leq \frac{a_1+a_2+\ldots +a_n}{n} By induction, I started by showing it for n=2...

Probability gets interesting? Hey guys thought this was an interesting problem that our lecturer purposed: Pick any word in the first few lines and do the following: Let’s say your choice is the word “shadows”. This word has seven letters. The seventh word following “shadows” is “all”...

Homework Statement A block having mass m and charge +Q is connected to an insulating spring having constant k. The block lies on a frictionless, insulating horizontal track, and the system is immersed in a uniform electric field of magnitude E as shown in the diagram. If the block is released...

I put an annoucement of this up in Announcements. There are some other links about it there, if you want more informaltion http://www.ccsem.infn.it/ef/emfcsc2008/pdf/Poster_ISSP2008.pdf What I want to do here is comment on the lineup of talks. The BALANCE in the theory topics is really...

Homework problem given by Count Iblis to the PF community: Consider a box containing a pendulum of total mass M in a spacecraft that is in free falling motion. Suppose that the engines of the spacecraft are turned on and the spacecraft is accelerating at acceleration a, where a is...

Homework Statement Homework Equations wave velocity = frequency * wave length The Attempt at a Solution Well...I'm not sure. I know how you could find the distance to the person to the right using trigonometric, but I don't know how to actually answer the question...

Come to know about any amazing plants(which do or have anything amazing) share it here!

An interesting Contest! I found this one interesting & easy; [PLAIN]www.ploysiam-gems.blogspot.com[/URL] comments welcomed.

I need to come up with a topic to present in one of my classes but I'm having a hard time coming up with something. I thought about doing a presentation on video security or how a cable box is securing the incoming video but someone else is doing it. I thought about maybe doing it on some type...

Say you had a universe, like our own in every way except that the total matter in existence was one single atom. Now say you introduced another atom of roughly the same dimensions into this universe as far from the original atom as spacially possible. How long, if any time at all, would it...

We look at a Laplace equation (\Delta u(x, y)=0) ) on a square [0, 1]* [0, 1] If we know that u|_{x = 0}= siny , u|_{x = 1}= cosy u'_{y}|_{y = 0}= 0 , u'_{y}|_{y = 1}= 0 we differentiate here by y. proove that |u|<=1.

:smile: http://funnyexamanswers.com/img/humandrawingis4.jpg http://www.funnyexamanswers.com/img/usecalctoproofofbatmanis.jpg interesting not exactly an exam answer but pretty interesting

Hi, I'm trying to achieve neutral buoyancy with a sounding balloon (a large latex balloon). Is there a certain weight/helium ratio that will make it afloat at 10km/20km etc (tyhe balloon bursting altitude is ~38km) One idea that I had was to attach another balloon, which is mostly empty...

In the past three days I have strangled my brother to death (he was being a right pain) Saved the world from annihilation with my super powers, and traveled to Liverpool (I can't remember why now, I remember I was staying there for a week for some reason) had a relationship which broke up after...

these are really intestesting but i have no clue what the answers are... 1. You are having some friends over, so you venture to the store to purchase some soda and snacks. Unfortunately the only pop available is at room temp. In order to cool the cans of soda quickly you place the cans in the...

AP Chemistry -two interesting questions -- PLEASE HELP! Homework Statement 1. You are having some friends over, so you venture to the store to purchase some soda and snacks. Unfortunately the only pop available is at room temp. In order to cool the cans of soda quickly you place the cans in...

how can I show that ... arctan(1/v) = (π/2) - arctan(v) ?

how can I show that ... arctan(1/v) = (π/2) - arctan(v) ?

Hi there I need some advice, please: can you suggest any interesting cases of a driven, damped harmonic oscillator? I need to write a report (part of some assignment) on the mathematical model/behaviour/etc. of some real-world driven oscillator. No problems with the math, I'm just looking...

Q1: What is the box suggesting? http://img231.imageshack.us/img231/1514/whatistheboxsuggestinggy7.th.png a-126485704 b-673258719 c- 123456789 d- 627456934 e-176h54308 Q2. What is the fourth sequence in the following: 1.BRRRRRBB 2.RBRBRRBR 3. 4.? a- BRRRRRBB b- BRRBRBRR...

Can you make the following message unhidden? Niuzmzgd ffccul vgeen ffmal ffuzmzal jcd niuzmzgd vhmmni ognh Hint: O,I,U,Y,T,W,A,H,X,V,M

I've been re-reading https://www.amazon.com/dp/0465026567/?tag=pfamazon01-20 and came across an interesting algorithm. Start with any whole number. If it is even, halve it. If it is odd, triple it and add 1. Repeat until the number reaches 1. Count # of steps it took. Number/Count...

Very interesting... http://icanhascheezburger.com/2008/01/16/funny-pictures-i-sees-it-i-grabs-it/"

Homework Statement Let \Omega be a bounded domain in C whose boundary is a curve z = z(t), a<=t<=b, and let A(\Omega) be the area of \Omega. Prove that A(\Omega) = \frac{1}{2}\int^b_a |z(t)|^2 Im(\frac{z'(t)}{z(t)})dt Homework Equations The Attempt at a Solution Not even sure...

Finding Tangents... Interesting ! Hello, I have an interesting problem for you. I have a surface & an external point which is outside the surface. I need to find the equation of all the tangents on this surface which pass through the external point. Regards, AtulSharma

here is a relatively simple problem that is actually quite helpful and interesting. NOT HOMEWORK, i already have the solution, just a little problem for u guys. a small sphere is released from rest, and, after falling a vertical distance of h, bounces on a smooth plane inclined at an angle...

Hello All, I was doing some research on different particle accelerator designs when I came across this interesting patent here: http://www.google.com/patents?id=FkYxAAAAEBAJ&dq=3935503 They claim in the patent that the device, using a rotating magnetic field, has the capability of...

Prove that sequence x_n=\frac{n}{\sqrt[n]{n!}} is increasing and \lim_{n\rightarrow\infty}{x_n} = e My attempt: First, I try to prove \forall n\in N:\frac{x_{n+1}}{x_n}>1. \forall n\in :\frac{x_{n+1}}{x_n}=\frac{n+1}{n}\frac{\sqrt[n]{n!}}{\sqrt[n+1]{(n+1)!}}...

I had a little insight, and I'm curious whether or not it's true. What I conjecture: Say we have a set of functions S = {f(a, n) = b_n * a^n + b_n-1 * a^n-1 + ... + b_0} where a and n must be both natural numbers, and b must belong to {-1, 0, 1}. Then for fixed a = a_0 and n = n_0, we...

http://arxiv.org/PS_cache/arxiv/pdf/0712/0712.2865v1.pdf New Frontiers in Cosmology and Galaxy Formation: Challenges for the Future Authors: Richard Ellis (Caltech), Joseph Silk (Oxford) Comments: To appear in "Structure Formation in the Universe", ed. Chabrier, G., Cambridge University Press...

Do you have some interesting ideas for extracurricular physics project - i am high school student, but i know basics of calculus and have very good knowledge in general physics...

http://video.google.com/videoplay?docid=-7955669901632007410 Edit: Apologies (and I won't let it happen again). Essentially it is just a short video of a Hungarian woman explaining her experience with socialism. I just think it gives one a look into what life life might be like in such...

Well, geostationary satellites are satellites which moves around in the same manner as the earth. This is true. and the derivations indicates that the centripetal force are provided by gravitational force of the Earth on the satellite which causes the circular motion. However, the Earth...

I have been trying to see how it can be proven that a power of 3 minus a power of 2 (or a power of 2 minus a power of 3) can give you every number which is not a product of 2 or 3. I just don't see how to prove it. Does it have something to do with the fact that you can get 1 as 3 minus 2? By...

Dear Folks: I have been experimenting with composite conductor materials for a while, but have had little success with getting conductivity below 200 ohms/cm. Polystyrene gel is easy to make and offers recycling opportunities, so I have been using this as a starter binder. Found that if...

Great pointers Dave, that will be easy to find. Perseus is not that hard to see. It is one of the circumpolar constellations, so is pretty much always in the sky, northern hemisphere of course. Has anyone observed a blink of Algol? That is one of those things that I have always wanted to see...

[b]1. How do you prove, using SD, that ((A>B)>A)>A? [b]3. I tried to first assume (A>B)>A. Then I made a sub-derivation, assuming ~A. In this sub-derivation, I need to derive a contradiction. How?

Hi, I got hold of a set of kitchen weighing scales which are made of some ferromagnetic plate and my neodymium magnets. So the reading on the weighing scales increases as you bring the magnet near the weighing plate, as expected... they then reach a maximum just before you touch the magnets...

A pyramid ABCDS is given (the base is convex quadrilateral). A sphere is inscribed in this pyramid and it is tangent to side ABCD at point P. Prove that \angle APB + \angle CPD = 180^{o}

We have NEVER experienced the physical world around us. Everything we have seen, have heard, have smelled, have tasted, have touched...has all be experienced from within our brains. You are NOT seeing these words on a computer screen in front of you, you are seeing these words INSIDE your brain...

Homework Statement A solid sphere is placed in an otherwise uniform electric field. Its upper half is made up from a material with dielectric constant e_1; the other half has dielectric constant e_2. The plane at which the parts of the sphere intersect is parallel to the uniform field at...

Hey, I just wanted to know what people think are currently interesting research topics being investigated in the fields of physics, applied math , or engineering which involves math (obviously), new technology, and is very much applied in nature? Thanks.

Hi all, thanks for reading. This is from my High school AP physics lab and I really couldn't figure out what to do we attempted to solve this by actually doing the lab instead of using math (which is what you are suppose to do) I would love to see the mathematical explanation of this. I...

Homework Statement There is a homogeneous rod stabilized on three fulcrum points. The separation of the fulcrums are of different distances. What forces act in the individual fulcrum points, if the mass of the rod is m? [The rod has to be stable, and hence the net force, torque = zero]...

This is my problem: 1) Suppose that the function y = f(x) satisfies the equation x^3+y^3 = 3xy and is differentiable. Find a formula for the derivative y' showing it dependent on x and y. Well, I really don't know what to do but here goes... Is it y' = f'(x) = x^3+y^3 = 3xy Then i...

Find a fairly bright light source around your home, such as a lamp. The closer your eyes are to the lamp, the better you can see this. A couple feet should work well. Hold up each index finder so they are a couple inches apart, and place them only a couple inches away from one of your eyes...

From Resonance(s) http://resonaances.blogspot.com/2007/09/drowning-hierarchy-problem.html Extremely contrived, sure, but it actually does better than RS on a number of astrophysics constraints. Gia will give a talk at my university sometime this year, i'll be sure to get more details then.

Hi This small video show you how to differentiate between a Raw and a Boiled egg in a very interesting manner ..enjoy http://www.metacafe.com/watch/809100/is_it_raw_or_boiled_enjoy_physics/ worthless link deleted Thank you

Homework Statement Firstly, I'd like to point out that this question is a little left of field...but here it is anyway. Here is what Puck has to say at the end of A Midsummer Nights Dream If we shadows have offended, Think but this, and all is mended, That you have but slumber’d here...