Interesting Definition and 790 Threads

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...

Out of the millennium prize problems, what one do you think is the most interesting/important?

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...

I am really sorry for posting this general topic here :redface:; I couldn't find any other place. So, here's what I observered: The rate at which new people join this forum is exceptionally high during this time of the year. So, just wondering why?

http://backreaction.blogspot.com/2007/07/consistency.html Bee took the time to write a thoughtful essay about general relativity and why you might or might not want to quantize it---and some broader thoughts about theories (what their limitations are, how you verify them.) Perhaps I am not...

Homework Statement For what natural numbers n is (10^n)-1 divisible by 73? Homework Equations N/A The Attempt at a Solution I have already found that it holds when n is a power of two greater than 8. (That means when n is great than 8, not the eigth power of 2) What other natural...

The textbook states something along the lines as prove the identity. 1 - ((sin^2x)/(1+cos x)) = cos x If you want you an work this out algebraically relatively easily to get cos x = cos x. But what if you put pi back into the original equation? You get 1 - undefined = cos x. So I graphed...

1. The A mathematically inclined friend emails you the following instructions: "Meet me in the cafeteria the first time after 2:00 p.m. today that the hands of a clock point in the same direction." When should you meet your friend? 2: : (hr : min : sec) I have attached my attempt at a...

"Yes, when I take my dog for a walk," said a mathematical friend, "he frequently supplies me with some interesting puzzle to solve. One day, for example, he waited, as I left the door, to see which way I should go, and when I started he raced along to the end of the road, immediately returning...

If you have a chain of links of equal lengths whose ends are connected (so that it forms a loop) then by holding three points and "pulling" them outwards different triangles can be formed. For example, with a chain that has three links 1 triangle can be made. With 4 links no triangles can be...

Which state in the USA is the most interesting one to live in, in terms of having things to do and see?

so I'm having trouble with an integral. However I noticed an interesting property to it.int{gdu}=c*int{gd^2u} with the integral being from -infinity to positive infinity. The problem arose while I was trying to solve the schroedinger equation in the presence of a potential, I'm trying to...

we have to prove that 10+100+1000+10000+100000+...=-(1/9) any ideas?

Hi... Many times I have read articles about how strange inertia is and that no theory we have so far can not explain it etc. However I don't see that problem with it. What is so weird on inertia? It seems to me as normal thing that if some reference frame accelerate the particles in this...

Greetings, I learned that the speed of gravity is the speed of light as einstein predicted that once the sun disappears, the Earth would not instantaneously fly out of its orbit but only after an approximate 8 mins then the Earth would spin out of its gravitational field tangent to the circle as...

This is a problem was thinking about. If I have a capacitor and fill it with a dialectric of some dialectric constant (the dialectric fits perfectly and is mounted via a frictionless bearing so it can move freely). How fast does it move?

Homework Statement There are n > 3 points in the plane such that any three of the points form a triangle of area \leq 1. Show that all n points lie in a triangle of area \leq 4. Homework Equations None. The Attempt at a Solution This is hard to discribe since it is...

http://motls.blogspot.com/2006/12/lorentz-violation-and-deformed-special.html

I don't like electronics at all.However,it's an interesting question.For OR operation standard circuit,there are two diodes which are forward biased in 1-1 state.I cannot draw the circuit here;but anyone familiar to the circuit undearstands that even if the two diodes were not there, the OR...

Interesting lemma If P.Ferma knew the proof of the following lemma "Lemma. If numbers a, b, c, have no common factor, numbers c-a and c-b are also mutually-prime and n is odd, then the numbers (c^n-a^n)/(c-a) and (c^n-b^n)/(c-b) are also mutually-prime", then with its aid it is possible to...

Hi, I was wondering if anyone could give me some advice as to how to go about this. This seems like it might fit under more than one discussion category, but astrophysics seems like it might be the best place. I'm a programmer, and what I am trying to do is to write some software to generate...

Find a general equation of geodesics on cylinder's surface. What's the name of these curves? :cool:

Hi Everyone, I think I've solved the equations of motion for a particle in this one-dimensional potential - V(x) = -k/(a-x) - k/(a+x) with |x| < a, a is real +ve, x is real. K is a constant of suitable dimension. It's a charge between two like charges with separation 2*a. I start...

I have some quotes from various books I have read recently, that I would love to hear your thoughts on: Richard Feynman: "All these [chemical] rules were ultimately explained in principle by quantum mechanics, so that theoretical chemistry is in fact physics. On the other hand, it must be...

Interesting Question... If I were to tie one end of a rope (a very very long rope) to the ground and the other end to a rocket, and fired the rocket into space, would the rope stay in orbit without falling back down to earth? Assume once the rope was fully vertical that the rocket was...

Hey guys I have an interesting topic for all of you who interested. From the EPR paradox we know that principle of non-locality indeed exist and yet it is suggests that information cannot be transferred between A and B due to quantum mechanics uncertainty principle since information gets...

Today my wife and I got into a little discussion on calorie intake and weight gain. A dietitian will tell you that if you take in an extra 3500 calories a day in your food, you will gain an extra 1lb if you do not burn off that 3500 calories. This is usually true, since there is no food out...