Thread Definition and 503 Threads

Horizontal Waterwheel (from: "centrifugal force" thread) This is all over my head, but I'm in the water and I want to learn,:eek: Maybe you guys need a mechanical challenge to apply your classical physics to:rolleyes:. I know very little of what has been said, or how to make calculations...

Post any thing you want to build but have not time/resources to do so, I want to build a three wheeled electric powered car, i have ideas to make it a practical home build project, first the body will be a monoquoc made from ply wood, the front suspension will be a (unit) that bolts to the...

I am starting this in analogy with "the Food Thread". The point of this is to thread is to house people's comments and to collect their resources and to foster discussion about the highly important and relevant-to-our-daily-lives topic of human nutrition. I want people to post here particularly...

So, I am attempting to learn linear algebra on my own and I am using Sharipov's "Linear Algebra and Multidimensional Geometry" since mathwonk is always ranting and ravong about it. So far, I hate it. Clearly I am not a mathematician at heart. I thought I could periodically post questions...

OK. I am coming back to CA, U.S.A. after several years for university from another country. I left U.S.A. about 10 years ago. And now that I am coming back there are many things I need to learn. So I thought this would be a good place to learn about the general things I need to know. So...

Every once in a while, a thread comes up that has 'something' to do with the 'Arts'. Past ones had the 'chicken' on the roadside, discussions about Pollock, avatars, etc. So, I thought this may be interesting. From paintings to film to dance to your or your child's art, whether a...

I filled the kettle ready to make coffee then the phone rang, after taking the call i wondered why the kettle had not boiled, the kettle has an indicator light to show it is switched on, the kettle felt cold 5 mins after i filled it, so i got the meter out and started testing the element etc...

Homework Statement Two boxes $A$ and $B$ are connect4d by a lightweight cord and are resting on a frictionless surface. The boxes have masses of 12.0 kg and 10.0 kg. A horizontal force $F_p$ of 40 N is applied to the 10 kg box. Find the acceleration of each box and the tension in the cord...

Motoring. With fuel prices so high it seems a good idea to try every way we can to save fuel, Are there any TESTED methods that save fuel, any gizmos that actually work? Take for granted that your vehicle is in top running order, engine tuned, brakes running free, tyres at correct pressure etc.

There has been a spate of writing in the popular media about the debates between scientific teams regarding various WIMP (Weakly Interacting Massive Particle) detection devices in the search for Dark Matter. (Example: http://www.nytimes.com/2008/04/17/science/space/17dark.html?ref=space from...

oohh nnoo another "i want to quit smoking" thread Guys, I haven't smoked a single cigarette since three weeks now ! I have decided to keep up with the no smoking policy in my life. Some effects : i eat twice as much, i have twice as much energy and it seems to me that i am tasting my food...

Hi, Homework Statement Just having some troubles with a proof i have been asked to do, (sorry for not knowing the math code) basically, f(1)=0, f(2)=1/3 and f(n)= ((n-1)/(n+1))*f(n-2) and I've come up with the conjecture that f(n) = 0 when n is odd, and = 1/(n+1) when n is even...

FranzBear lives again!

Greetings, 2+ months ago, someone posted old entrance exams to a graduate school (physics) I think it may have been USC but I'm not sure. I didn't download it and now I can't find the thread with the link Can you help? Thanks Sparky

:biggrin: Well, we have a food thread, but chocolate is a special case. I was watching a news program during a flight yesterday, and one of the pieces was about the Valrhona company, which makes gourmet chocolate. So I thought it would be appropriate to start a chocolate thread -...

This thread is for anything related to Photography. I am quite new to photography and I do not know a lot about it, so any pointers would be great. I've seen some really great shots in the competition threads, so let's see what PF has to offer :cool: [SIZE="4"]Hosting your Photos I use...

Homework Statement 6^1+6^-1 / 6^1-6^-1 (Question is to evaluate that, but I am going to venture to guess that we are supposed to somehow simplify the question a lot further. We just finished learning all the exponent laws) Explain how you can tell which is bigger without evaluating...

I did think about high guard armour, but that is not invented yet, any other full body protection is rather cumbersome, so what are the options.

Can you help me with some of these questions? I can't do the second part of Q1!

Consider: space aliens have today announced in all languages that on January 1st, 2125, they will descend upon Earth and vaporize all paper and metallic money that is in use at that point in time. Given the above scenario, how much is the money in your wallet worth today? What is your...

Well anyways.. I'm currently a student at a High School. We have these "Scrap heap challenges" The idea of this one is to build a "Electromagnetic device" This one is to hold at least 5 grams of weight and maintain it.. After that we keep adding weight to see who's can hold the most With...

I know these grad school threads have been overdone but nobody ask this question yet: Would it be fair to say that the grad school applications commitee looks at : 30 % gpa 30% GRE score 30 % Research experience 10% letters of recommendation?

Hi, Please help me in finding thread length engagement. Please find attaché image I have a product comprising of 2 parts fastened together. Hydraulic fluid is passing thru it. My inputs- load, size of the fastener used (ex: M8 X 1.5). My constraints are-the boss length should be...

You can post anything to do with Christmas/Hannukah/Yule Goats, etc... here. No religious preaching, we're talking Santa and reindeer, elves, goats, socks and chocolate coins, ok? To start off, since my favorite video was deleted from youtube thanks to a company that misses the point of free...

was deleted?

I was just in a thread over in the Academic and Career Guidance forum asking if there was a special thread for listing possible scholarships. I noticed there wasn't one stickied, so I thought I'd ask to see if it would be feasible to get a thread like that stickied in that forum. I think it...

Is there a thread/forum for science Scholarship advertisements? My supervisor has asked me to advertise PhD positions in Quantum Information science on the net.

In this forum there was one problem. Two heavy balls of equal mass M are attached to long light rod. The rod is held vertical and allowed to fall, say towards right. What will be the speed of each ball just before the upper ball touches the ground. I can interpret this problem in three...

I so happen to like visual brain teasers. There's a lack, not to say a total absence, of these on this forum and I thought it'd be a good idea to start this thread so to undo the injustice. I was thinking maybe we could have some mods readily check this thread to validate image postings. That...

Homework Statement Q 1. A spider with a mass of 0.26 g hangs vertically by one of its threads. The thread has a Young’s modulus of 4.7 x 10^9 N/m2 and a radius of 9.8 x 10^- ^6 m. a) What is the fractional increase in the thread’s length caused by the spider? b) Suppose a 76 kg person...

With all the brains about. I know most of you drink to your misery. Ignorance is bliss eh?

this has probably been done before, but I love talking about dreams! everyone has all sorts of cool dreams, and for some reason it's not something that people talk about nearly enough! my friends always want to hear my dreams (I have really really weird dreams), but then they never return the...

what did you do today? (a corollary to the thread "What do you physicists do?") I thought it might be interesting to take a sociological approach to the question raised by Pivoxa in this thread - https://www.physicsforums.com/showthread.php?t=186911 So what do physicists actually do on a...

No thread yet on the NFL? Between two channels, three game winning field goals in less than two minutes. Denver-Buffalo was first and best. They made a first down and could have spiked the ball to stop the clock. Instead, they rush the field goal team out with about 10 seconds on the...

(Separated from another thread) Hey i need some help finding the general solution of ydy= (-x+ √(x^2 + y^2))dx by using the substitution y= vx and then the substitution u^2= 1 + v^2 It would be great if someone could help.

Hi there, I'm sorry if this sounds incredibly vague, but I'm having difficulties narrowing down the research question for my Physics EE. I'm sure of the field I want to do it in: acoustics. The problem with most experiments involving applied acoustics (ideal room sound, etc.) is that, unless...

Shear thread formula? my group has been told to figure the shear stress of a thread for a hydraulic press which pushes at 100t, we have figured it will pull at 30t using the ratio of the areas from the pistions. just we need to figure the shear stress on the thread if it was to pull. we don't...

Well we have a food thread, a gardening thread, a wildlife photos thread, a best music/tunes thread, . . . sooooo :biggrin: Why not a practical DIY = do it yourself thread for sharing tips and info on home repairs and renovation. My home has a drainage problem. In a relatively dry area...

the Cosmic Variance blog has changed format and eliminated a nice feature that used to keep discussion threads alive. on the righthand margin of front page, it used to list which posts had recent comments and, in small font, WHO THE COMMENTERS WERE so if some interesting people, such as Lee...

ok well what happened to my thread i just requested sum help is dat to much to ask sorry for bothering u guys i just needed sum help thanks for nutin yeh i waited to the last minute but no ones perfect thanks for letting me fail and not even giving a beep

I need a 3/8-16 full thread (Tap) 1/2" long hex bolt with a left hand thread. Anyone know where I can get one without paying a minimum order fee.

Hello all, I also have a calculus thread in the appropriate forum- I wanted to have a separate physics thread in order to make things a little tidier around here! A quickie: A 1,200kg car turns a corner at 8ms^-1 and travels along the arc of a circle radius 9m in the process. How large...

looks like a cartoon bomb? one more thing what's with the additional rectangle icon on the right hand side?

Instead of cluttering the forum with all my cries for help, I decided to condense them all into one! First, I know this is basic, but I just can't seem to figure it out: Int (x^2+1)/x^2 dx Intx^2/x^2dx+Int1/x^2dx x^3/x^3+x/(x^3/3) ?? Thanks in advance!

Hi. I recently got a Toshiba M7, and been playing with it for some months now. What I've found is that the hardware is neraly there (calibration is my biggest complaint), but the software is really lacking. Currently I'm using Windows journal because OneNote 2007 is fu**ing slow. Anyone...

I need with a problem...A 0.10 kilogram solid rubber ball is attached to the end of an 0.0 meter length of light thread. The ball is swung in a vertical circle. point P, the lowest point of the circle, is 0.20 meter above the floor. The speed of the ball at the top of the circle is 6.0 meters...

The "I wouldn't eat that on a bet" thread. Inspired by Evo's recent purchase of a "food" product made with a lot of water and that may or may not actually contain ham, and her adventures with "jerky" made from a meat paste seasoned with pre-packaged spices (and God knows what else), I am...

Hi, I notice that there are many self-study students here on PF so I thought it'd be a good idea to make a quick reference of great books. Please add on as I'm currently only at the precalculus level. These books should assume relatively little to no prerequisite knowledge, explain concepts...

Hi -- Does anyone have torque recommendations for a 3/4-14 NPSM thread for S.S. and Aluminum? Thanks! Eric

i got some math jokes on my cmoputer. Some are alright, most are terrible. Ill keep adding some periodically. Feel free to post your own. Whats purple and commutes? An abelian grape. (i have no idea what that one means) Q: What do you get if you divide the cirucmference of a...