Flat Definition and 469 Threads

Is it even possible? Or am I just flat out wrong once again? Whenever I really need to procrastinate, I turn to writing a calculus book. In this case.. For about three days I pursued the problem of whether or not you can teach topology before "rigorous Calculus". Is it even possible, to...

Homework Statement A space-time is said to be conformally flat if there is a frame in which the metric is g_{ab} = \Omega^2 \eta _{ab} \text{ with } \eta_{ab} the metric in Minkowski. Is the general Friedmann-Robertson-Walkers space-time with line element ds^2 = -dt^2 +a^2(t)(dx_1^2 +...

Homework Statement http://mathworld.wolfram.com/images/eps-gif/UniversalCoverDoubleTorus_1000.gif Why do you need both the orange and the purple cuts to lay the double-torus flat? Why can you not connect the orange cut going right and the purple cut going left under the torus. It seems like...

I am trying to repair my 1920s pier and beam house and have a situation where I need to slide under two butted beams on top of a post the thinnest steel I can that will support the two beams. What would help me determine this would be a general idea of how to compare the strength of a flat...

I would appreciate help in objectively disproving the following "alternative physics" proposition: "The large-scale geometry of the universe is compelled to be eternally flat because gravity causes the universe to expand at exactly the escape velocity of its mass/energy contents." This...

A uniform flat disk of mass M and radius R rotates about a horizontal axis through its center with angular speed ωi. a) What is its angular momentum b) A chip of mass m breaks off the edge of the disk at an instant such that the chip rises vertically above the point at which it broke off. How...

shear stress, what is a flat tie bar...? Homework Statement two lengths of flat tie bar are connected together by a lap riveted joint with three rivets each 10mm in diameter. Calculate the maximum pull that can be applied to the tie-bars if the shear stress in the rivets is not to exceed...

pump add air into the flat tire in the gas station. The compressed air is at 180 psia and 60F(+460). the tire is initially at vaccum, therefore p0=0 psia. Air is added into the tire until it reaches Pf =32.9 psig which is (23.9+14.7=47.6 psia), then stopped . this process is adiobatic which...

I'm working on a computer simulation, but I'm not sure how to approach this problem. I want to find the change in angular velocity on an object rotating on top of a flat plane. So far this is what I have: (* == multiplication not dot product) Ff x r = I * alpha Ff x r = I * dv/dt I...

Ohh is this a joke? http://en.wikipedia.org/wiki/Flat_Earth_Society http://theflatEarth'society.org/forum// They even use physics theories to "prove" that Earth is flat. Comments? -link

I just want to make sure my understanding is correct. In a "flat" universe, the total density of the universe matches the "critical density". As a result, the universe will expand forever, and never "fall back" into itself. The shape of a flat universe, as the name suggests, is flat like a...

Homework Statement While coasting along a street at .5m/s, Mieko, a 15kg girl in a 5kg trolly, sees a vicious dog in front of her. She has with her only a 3kg bag of sugar which she is bringing home from the store, and throws it with forward velocity of 4m/s relative to her original motion...

Sorry for posting this in the wrong spot. Thanks for moving it. If there is a consensus throughout mainstream science that the Universe is flat, I have a few questions that I have not found the answers for.What types of explosions are flat? What forces are required to keep the universe flat...

Homework Statement A block of mass m is pulled along a rough horizontal surface by a constant applied force of magnitude F that acts at an angle theta to the horizontal. The acceleration is a. Express all algebraic answers in terms of m, F, theta, and a. A. Derive an equation for the normal...

Hi everyone, I'm puzzled by this phenomenon - when there's a thin sheet of water flowing in the street, it forms little wavefronts which appear periodic. Obviously the water gets thin enough to interact with the rough asphalt surface, but how does the random texture manifest an organized...

It seems to me that current thinking leans toward an expanding and accelerating universe that is neither positively nor negatively curved, but rather, essentially, 'Flat'. How does this thinking not contradict with the fact that gravity, which surely exists, is the curvature of spacetime in...

A map suggests that Atlanta is 730 miles in a direction of 5.00 degrees north of east from Dallas. The same map shows that Chicago is 560 miles in a direction of 21.0 degrees west of north from Atlanta. Modeling the Earth as flat, use this information to find the displacement from Dallas to...

I know that the water vapour condenses once it hits the colder air above. What I don't understand is why the warm-colder boundary is always parallel to the ground even while the masses of air are pushing through it. Why wouldn't the rising mass of moist air also determine warm-cold boundary...

Does anyone know where I can find a flat tiny speaker, let's say for arguments sake roughly the size of a quarter, that can produce a reasonably loud audible tone? Thanks! Ted

One thing I think is a little bit funny (among a lot of other things). All the time I have learned and heard that the world is round, and when I travel with aircraft I can actually se it is at last courved. But when planning long distance travels I understand that it is quite round as it is...

I am really confused. Would you please tell me what the turbulent boundary layer thickness is on a flat plate? There is a well-known Schlichting formula in the previous editions of his book “boundary layer theory”, which is: \delta = 0.37 X Re^{-0.2} But actually I could not find this...

Can anyone help with how to find the analytical solution to problem involving finding the stress concentration around a circular hole in a flat plate. The plate is has tensile load on both sides.

I want to be able to generate pages from a database but the data only changes occasionally. It'd be more efficient to have the pages served up from flat HTML most of the time and only have to "publish" to HTML when I make a change to the database. Is there a really convenient way of doing...

Interpretation: The Cosmic Background Radiation is evidence of a flat universe. Problem: How does a teacher show that all the knowledge necessary for this interpretation does not require the assumption of a flat universe?

What does it mean for the universe to be globally flat, What does it mean for the universe to be globally flat, spherical or hyperbolic? How does it relate to whether the universe will recollapse, or never stop expanding, or expand at an accelerating rate? How does it relate to local...

Can someone please tell me, the coordinate transformation that will make the following metric: ds^2=dr^2 + r^2d\theta^2 look locally flat? Many thanks.

I am required to analyze the physics for 4 scenes in the movie Top Gun. In one scene, Maverick's plane goes into a flat spin. Would it be possible for someone to explain this in from a physicist's point of view. Equations would be nice too lol. I am new to hpysics so please don't get mad lol...

It seems to me that people with flat feet should have been weeded out by evolution back in the day when they actually had to walk and run around all day long. Am I missing something? Aren't people with flat feet at a huge disadvantage in those conditions?

Do the matter and radiation of a flat universe, as time approaches infinity, conform to a spherical shell?

This is a bit of a lark, but I'm just wondering if I've understood correctly to draw my conclusion... It is my understanding that the curvature of spacetime postulated by GR is what causes orbits which appear elliptical. An orbiting body is following its inertial path which might otherwise...

How much net work is being done when a car is traveling at a constant speed on a flat road? I think there is not net work done. :bugeye:

Ok i can stand on a flat roof with some sort of wall or at least waist high railing around it, but i could not even think of standing on one without either, not even in the middle, crazy or what?

hello. I know when omega is equal to, less than or greater than one our universe is either flat open or closed respectively. omega is the ratio of the current observed density to critical denisty in the universe. my question is that we can only see our part of the universe (that is 13...

Hey guys, so I'm back in school after an 8-month break, and I'm feeling a bit rusty :rolleyes: So I've got a flat disc of radius A, with constant density p, in the z=0 plane. I want to calculate the gravitational field at any point up or down the z-axis. I integrated the potential over the...

Does anyone know where I can get a few 10-pin female flat ribbon cables. They look like this: http://hubbard.engr.scu.edu/embedded/lcd/lfh8p4032b/P1010029.JPG The header looks like this: [ooooo] [ooooo]

I have read from Universe by Freedman, Kaufmann that our universe is largly flat so it would mean there are edges in our universe. Our universe would be like a flat piece of paper that is continually expanding. A more realistic picture might be a diagram of Einstien's fabric of space time which...

I'm reading Parallel Worlds by Michio Kaku and I keep wondering if space is flat, then what would happen if you kept moving directly downward under our solar system (or directly down from any other planet)? What would you see and where would space end or simply curve back around. Thanks!

I realize this may be a really obvious question, but wikipedia and google haven't help settle my curiousity. If the universe is in fact a flat universe, as I believe has been proven with experimentation, this, if I am not mistaken, means the universe will continue to expand to a limit without...

We know if the Earth is considered flat the maximum range is obtained when the missile is launched at an angle of 45 degrees. But what if we take into account the curvature of the earth? what is the maximum arc-length of the range? :confused: Thank you!

We know if the Earth is considered flat the maximum range is obtained when the missile is launched at an angle of 45 degrees. But what if we take into account the curvature of the earth? what is the maximum arc-length of the range?:confused: Thank you!

For a beginner (as I am since a long time), it is convenient to conceptualize curved spaces as embedded within a familar flat space with more dimensions. Of course the intrinsic point of view is more elegant and suffice to itself. Nevertheles, I am asking this question: are there some curved...

If the emissivity of a flat surface varies with zenith angle according to e=E*cos(theta) where E is the emissivity at zenith. Would this surface radiate isotropically? I think that because the emissivity varies then the emitted radiation varies accordingly so the energy measured from...

Why are the bottoms of large clouds flat?

So why exactly does the military refuse you if you have flat feet? My friend is trying to join the US Marines but they refused him because he has flat feet. Does this make you unable to do something required of a soldier or what?

If you have ever seen a tall chimney fall, you will have observed that they break up on the way down. This is because of the effect you have found. What is even more interesting a cylinder falling in that manner will break into 3 large pieces and some crumbs (about .14 ) so the chimney...

hi, for most of you this might be a simple question: Is it possible to embed the flat torus in Euclidean space? If we, for example, take a rectangle and identify the left and the right sides we get a cylinder shell, that can be embedded easily in R^3. If we construct the...

I had a flat last week. Today I just went and got the spare fixed, so I'll be ready for the next flat. I get about two flats a year. That seems high compared to most people I know. The reason I have so many is that most of then come from driving my pickup to the landfill where there are always...

and does not slide off. in this case does centripetal force = frictional force? I think the answer is yes, but want to make sure. thanks

I am a trying to work out a design issue that you may be able to help with or maybe point me in the right direction. I am designing a 17-4 stainless steel plate to be used to support a trust bearing. The dimensions are 3.333 inches in diameter with a 1.20 inch center bore and .097 inches...

U. S. corporations paid 60% of the budget 50 years ago compared to 16% today. Would a flat tax introduce a more fair distribution? (Another example of corporate rights overtaking individual rights.)