Fun Definition and 428 Threads

I was looking through some problems on QFT, and I found these exercises: http://www.damtp.cam.ac.uk/user/tong/qft/oh4.pdf I was wondering about questions 9 and 10... Q9 : speaking I guess aftermatch ,why was there a factor of 2 wrong in the published result? To be honest I don't quiet understand...

Homework Statement Homework Equations I = nqVA J = E/ρ J = I/A The Attempt at a Solution The underlying assumption was that current was constant across all 3 bits of the conductor, and thus answer is b. The concept I can't grasp is this: Why is current constant? Shouldn't a smaller A mean...

I’m looking for books of a general interest in maths, like a maths novel, a fun book about maths, a humorous introduction to higher concepts, something outside of tests, something they can read on their free time and appreciate the beauty of mathematics. Let me add more details. I’m working as...

Trying to solve this problem: Mixtures are made from 18 different color paints. Every mixture has 6 different colors. Every combination of 3 different colors is contained in at least one mixture. What is the minimum number of mixtures that can be formed? Example: If the problem...

I wonder if anyone has some fun or interesting stories about their high school or university physics teachers. In my case there are several, and some of these teachers had tremendous reputations. These were actual professors of mine, so I know this is not apocryphal. Of course I will never...

Hey folks, I recently made a little equation and I would like to know if there's any way to plot it on a 2D graph. Problem is, there's multiple variables. so if anyone here can help me out that would be appreciated. Here's my formulas: S2 = (S1-(S1/10))/2x x= T2/(S1/20) T2= T1-(S1/10) S1 is...

I like well done visual displays of science. Lets see what other people can come up with! Here's one I found, overlays of the night sky from Australia, in false color of a wide range of radiation frequencies.

Inspired by this SMBC comic: I can read things some people can't read so I read them and then write them again only now those people can read it. Now's your turn.

My friend asked me this question the other day , and although it sounds simple and foolish i was unable to find an answer to it even after hours of internet research . my friend said that us humans can feel joy and euphoria and that's actually what drives most of us in life . now less...

Imagine a fish in a tank that is completely filled with water and closed on all sides. Can this fish swim? Since water is extermely difficult to compress, when the fish moves its fin to propel itself forward, the water can't move anywhere, so the fish should not be able to move right? Then I...

I have a user input of 2 integers (m,n) Then my system will generate 1 list of M (m,n < M) integers that start at m and end at Mth integer of value xM. The formula to calculate xM is followed by x_0=m x_M=x_{M-1}+n After the list is generated I randomly delete N (N << M) rows from it and given...

B b-a D a c-b+a C b A Right triangle ABC, with the standard a, b, c side lengths. Angle BAC = 2u degrees. Point D is on the hypotenuse AB, such that: BD = b-a, angle BCD = 3u degrees. Calculate u.

Some of us are big time into home theater stuff and recently a question came up that I figured somebody here could solve if they wanted to. Basically I'm wanting to know the force exerted on a subwoofer enclosure when at max excursion. Some of the known parameters: this is for an 18" Ultimax...

Hello Everyone! My name's Christina and I work at the Everyman Theatre in Liverpool... We have a show coming up in the main space at the beginning of July that's going to be performed by YEP (Young Everyman and Playhouse)... and hopefully it's going to be a love story about all things Physics-y...

<Moderator's note; thread forked from https://www.physicsforums.com/threads/question-regarding-the-dirac-delta-function.866220/> Why do you say that? The function that takes a function f(x) and returns f(0) is a well-defined distribution. Maybe what you mean is that if we identify two...

Explain the physical process of the tongue action of a dog drinking water. State yr answer then watch the clip to see if you got it correct. Secret Life of Dogs: Alsatian dog drinking water …:

so far I have come up with 5 possibilities Are there more ? what one/ones did the originator think of ? I won't post my answers till I see a few responses Dave

Hey guys, new here :biggrin: Just started a kinetics course and I'm looking forward to discuss the meanings and maybe get some examples of the kinetic equations and graph's I'll encounter (just finished the time distance stuff) pardon my newness to the world of physics, this would be my first...

Hi, my name is Noel, i am currently a final year student , in newcastle university majoring in offshore engineering! i love to play dota, going out to watch movies, listening to musics and love reading book. I hope to make many like minded friends through this forums and finally NICE TO MEET YOU!

I thought of explaining galilean relativity to a layman like this: "A person is heavily drunk and he revolves, revolves and revolves. He shouts," The world is revolving around me". You are bystander and u say," you drankard, the world is not revolving, but you are the one who is going in rounds...

There is a set of 16 polynomial curvature scalars called the Carminati-McLenaghan invariants: https://en.wikipedia.org/wiki/Carminati%E2%80%93McLenaghan_invariants . For some fairly broad classes of spacetimes, they are supposed to give enough information to distinguish one spacetime from...

If so, I have an account on lichess.org. My username on that site is mulah_aprilclimate. If you're in the mood to play, please shoot me a PM and let me know you're from physicsforums! My US Chess Federation rating was between 1800 and 1900, but I haven't played in any tournaments in over a...

Hey folks, found a couple of interesting integrals and was able to solve one of them ANALYTICALLY! That means no numerical solutions needed. $$\int_{0}^{\frac{\pi}{2}} \frac{1}{1+(tan(x))^{\sqrt{2}}} dx$$ $$\int \frac{1}{1+e^{\frac{1}{x}}} dx$$ The first one I solved and will reveal analytic...

Context: I'm an artist working with a writer on a superhero comic. One of the characters we were thinking of adding is a person with electricity powers. However, the writer wants the electricity powers to be somewhat more "realistic" (at least, aside from the whole electric super-powered human...

Mid Saturday morning and the radar was telling the story, a large and long storm front line was stretching across SE Australia and was very lightning active. Said to my wife, Cindy, pack an overnite bag, we're going stormchasing and probably won't be home till Sunday nite. 300km or so of...

klotza submitted a new PF Insights post Fun with Self-Avoiding Walks Continue reading the Original PF Insights Post.

The question being is it harder for a forklift to lift the same weight farther out than in closer? An example say you put 3000 lbs on the tip of the forks, does that require more effort/strain/hydraulics to lift vs 3000 lbs positioned closer to the lifting cylinder?

It's harder than you might think. https://en.wikipedia.org/wiki/Meaningless_statement 'Twas brillig, and the slithy toves Did gyre and gimble in the wabe: All mimsy were the borogoves, And the mome raths outgrabe. ... and so they should!

http://www.travelportland.com/article/world-naked-bike-ride/ It's expected to be 103 that day so stay hydrated, riders. http://imgick.oregonlive.com/home/olive-media/pgmain/img/ent_impact_home/photo/18181464-standard.jpg

Hi, i am studying because i think it is fun! I might ask some astronomy and mathematics questions, but mostly physics!

Tell me what fun I will get over here

What if the Friedmann equation told how the (square of) fractional growth rate of spatial volume relates to the energy density, instead of describing how the (square of) fractional growth rate of spatial distance relates to energy density? Just two slightly different ways of describing the...

Homework Statement My homework question says: the uncertainty in length 1 is +/- 0.1 and in length 2 is +/- 0.1 : calculate the percentage uncertainty in V where V L1-L2 is 30Homework Equations V= (1/(L1-L2))^0.5 where L is the length[/B]The Attempt at a Solution So what I did was add...

Hi guys, I came across a really interesting thread in the Internet where the author was asking for fun, but serious Maths book recommendations. I saw plenty of excellent books being recommended there and thought I'd start a similar thread over here :) Some characteristics of the books should...

Homework Statement The electric field is described by E = \frac{C e^{-br}}{r^2} , find the charge density and then integrate over all-space and show it's zero. [/B]Homework Equations E = \frac{C e^{-br}}{r^2} \\ \\ \nabla \cdot E = \frac{\rho}{\epsilon_0} \\ \\ \rho(r) = Q \delta^3...

Say i m in the cinema and there are 4 seats. say the closest seat is the best view which is 4 meters away. say the further the distance away the worse the viewing quality. eg [5,6,4,9] are the distances of seats away from screen. Now let's say people sitting in front of you also effects viewing...

Prove that $\lim_{{n}\to{\infty}}(3^n+4^n)^{1/n}=4$

enjoy :)

hi

Hello everyone, First up, I know nothing about physics or chemistry. That out of the way, let's begin. I recently read about a very interesting material called Starlite which is supposedly a remarkable thermal barrier but is presumed lost to the world because the inventor kept the formula...

Welcome friends to the world of physics

Homework Statement Homework Equations phase constant: y= Asin(wt +phi) The Attempt at a Solution 2*sin(360) =0 How does one approach this problem?

I'm thinking about doing some research in math next semester... pure math, focused on Algebraic Geometry. I'm currently doing research in theoretical cosmology, and it's been going really well, but the math research sounds really interesting to me. What would grad schools think of this? On one...

Hello, I'm looking for any ideas that you geniuses may have! We have to design a device that will catch a (hardboiled) egg from 7 meters high. It can be made from any material/objects but must be under 5 cm tall (the sides can be as wide as wanted) and must be self-supporting. The device will...

I am almost finished pre-calculus and I am wondering when math will become more enjoyable. I feel like everything about math up to this point seems like a chore. I absolutely can't stand graphing function after function, it just seems like such an incredibly mundane thing to do. I keep...

Hey all! Did you know that one of our members (http://mathhelpboards.com/members/mathmari/) created a new math web site, just for fun? It's here: The Magic of Mathematics - Home Anyone feel like posting something (that is, using the contact form) there? ;)

Putting a Human in Superposition I recognize the practical aspects of this would be absurd, but I must admit the premise of what it would take to put a human in a superposition of states is an amusing thought exercise and has some relevance towards me understanding actually in what scenarios QM...

I was debating putting this up in General Physics, but since I already know the answer, I thought I'd put it here. I also put this in some other places to see how different forums would react - my own little experiment. =========== A true story: I once took a car GPS with me on an airplane...

Hello everyone, I am an aspiring math teacher taking a workshop type class and in two weeks my group will be teaching the other students various topics on probability. We are trying to come up with a fun and interactive way to teach the counting principle, permutations, and combinations. To...

Howdy, I didn't find anything particularly useful when I searched for this, which surprised me! Anyway, over break, I decided to buy my textbooks early and to semi teach myself the basic concepts before I actually take the class. And as break is coming to a close, I looking back and I...