Challenge Definition and 911 Threads

Alright, well seeing as my last challenge lasted a whole 30 minutes before Jimmy Snyder solved all my brain teasers, I dug deep to find more challenging ones. :rolleyes: :smile: Please use and and the closing tag [/ color] to make your text unreadable to those who don't want to see the...

I have selected a few brain teasers at random for the most part that I found at least mildly amusing and that I could not immediately find in this sub-forum. I wouldn't say that any of them are very hard, but some require sideways thinking and I think that makes them fun to do. It is almost...

hi, i got a real problem. i have a question here and have absolut no clue what i have to do and which equation i have to use... ( for my shame, i was sick at that time we done it in school..) question: A diver is at the bottom of a lake, which is 10m deep. if he looks straight up he...

Disclaimer : This thread, and its solution, by no means suggests how to launch a network attack in real life. The purpose of this challenge is to learn how to decompose graphs and analyze them as efficiently as possible. There is no knocking down of network connections, or even speculations as...

Hey guys! I have an assignment similar to this: http://www.physics.uwo.ca/science_olympics/events/grades_11_to_12/yo_yo_challenge.html I don't really know how to go about building this. From looking at the nesessary equations (moment of inertia, etc.) it seems to me that the performance...

kepler's law! hi, does anybody know how to prove that the eccentricity multiplied by the directrix is equal to [itex] \frac {b^2}{a} [\itex]? i found that the eccentricity of an ellipse is equal to c/a. i also found that the directrix is equal to a/e. the way i see it, if i multiply e...

Ok so the question is, "A skier of mass 60kg, initially at rest, slides down from the top of a frictionless, icy, hemispherical, mountain with a radius of curvature R of 100m. a)Draw a free body diagram and write the Newton's Equations at the moment when he/she is at some point below the...

Dear all Math students : here is a challenging program needed to be run using matlab well i am presenting part of the solution and looking for the support from all of to reach the rest of the result >>>>>>cooperation is being seeked: generate binary data b_k using randint. 2...

So my dad gave me this problem because he likes to bother me: Explain why this is funny: click on it to see a big picture since it won't let me do it this way :/ Does anyone get the joke?

I'm working from H.M. Schey's Div, grad, curl, and all that, and am trying to figure out surface integration. One of the example problems boils down to the following surface integral over a projection, with z = 1 - x - y \sqrt{3} \int \!\!\! \int_R 1 - y \,dx \,dy I made x and y go from 0 to...

Hi, I just popped into see if there are any budding young engineers here (hope I got the right forum) interested in helping with a problem that I have been nutting out over the years... Hope your forum can help. It is all about controlling sway and buckling of members and gaining the full...

hi how r u all i have a small problem with this proof i want the solution without using double integral that `s the proof http://s07.picshome.com/ce2/aaa.jpg

I've spent about 6 horus this weekend trying to construct to build a paper tower that will support thick textbook 14 inches off the ground. the requirement is that it weigh less than 15 g. you can use tape and paper and that's it. Cylinders cannot exceed 5 cm in diameter. Tried making a bunch...

Hi, I have no idea of this ±.03 :cry: A population proportion is .40. A simple random sample of size 200 will be taken and the sample proportion 'p' will be used to estimate the population proportion. a. what is the probability that the sample proportion will be within ±.03 of the...

I’ve dropped my Calc II class because my Calc I class, which I took at the community college, never covered anti-derivatives, and my Calc II class started off assuming you already knew anti-derivatives and integration. So now I have the fun task of teaching myself anti-derivatives and...

I rarely care enough about one problem to ask for help, but there are a million problems that are similar to this one and I don't really understand any of them. The problem I'm looking at reads: In a room there are 10 people, none of whom are older than 60 (ages are considered as whole...

Hi, I just had a question i had trouble answering, I am sure its an easy one, but i can't get it, (since I am just starting physics): a bus starts at rest and accelerates at 1.5m/s^2 until it reaches a velocity of 9m/s. The bus continues at this velocity and then decelerates at -2m/s^2 until...

http://www.gravitation3d.com/magiccube5d/ Only 3 people solved it so far.

Here's the question from my text: "Alice and Bob are movin in opposite directions around a circular ring of radius R, which is at rest in an inertial frame. Mobh move with constant speeds V as measured in that frame. Each carries a clock, which they synchronize to zero time at a moment when...

Any enviromentalists do not look . So do you want a fast vehicle? i am trying to get a classic 1960 motorbike to go faster, i know it will never reach current motorbike standards, but it is the challenge, with some nostalgia ,that drives me, any engine gurus out there? if so your advice...

There's a lot of talk about "virtual particles" and of energy conservation within a normal perturbative approach to QM. I'm struck by the fact that there are precious little concrete examples or illustrations or gedanken experiments to support all the arguments, which go around and around and...

http://www.newscientistspace.com/article/dn9122-lunar-lander-is-nasas-biggest-challenge.html NASA's Centennial Challeges Program http://exploration.nasa.gov/centennialchallenge/cc_index.html

http://www.azcentral.com/arizonarepublic/local/articles/0510conspiracy0510.html As I have said before, this is an invasion, not immigration. In following the news of late, it is more and more clear to me that Mexico is a willing partner in crime in this issue. Also, the Minuteman group is...

Find the antiderivative of: -2x (1-x^2)^(1/2) That's -2x over all of that... Bleh, i suck at code. But anyway.. I just started integrals, and this is confusing for me... Is there a product or quotient rule in integrals like there is in derivatives?.. if not? how do you work...

Find the surface area when this curve is revolved around the x ax x = 1/3(y^2 + 2)^3/2 [1,2] I set it up both ways and i get two really complicated integrals. 2 \pi/3 \int_1^2 \sqrt{\frac{y^2+y^4}{(y^2+2)^{2/3}}} dy Yeah I can't figure out how to do this integral, and I am thinking there...

Can you count and add all the numbers 1-100 without using a calculator?

Putting E.S.P to the test by Physicist. I think we need a PF to choose Items of their choice and have all the people in the forum try to perceive the items by E.S.P (Extra Sensory Perception) just to see the ratio of results and post the end results when the item is perceived by a User, To...

Can anyone think of a way where friction increases the speed of a moving body, instead of decreasing it? Or prove that this is impossible.

i have to build a vehicle "powered soely by gravitational potential energy that will travel at least a linewar distance of 5 meters under its own power. no elastic potential energy (such as a mousetrap) allowed" i was wondering if anyone out there had any idea on where to start or knew of a...

I had planned to use spherical tyres for my engg. project on a robotic transport vehicle, but I'm stumped on how to get it done. Magnetic force could be an answer but monopoles are not possible...i'm stumped...Could someone provide me the answer:??:bugeye: thethi.hs@gmail.com

Dear all, I want to prove that the following inequalities are true. I hope you can give some hints. Thanks a lot! Define c_{\beta}=\sum_{j=1}^n \sigma_j^{\frac{2\beta}{\beta+1}}\sum_{1\leq i<k \leq n}\Big( \sigma_k^{\frac{2}{3(\beta+1)}} + \sigma_i^{\frac{2}{3(\beta+1)}} \Big)^3 ...

So, for whatever reason, I got to thinking. Let's suppose you have a 4 letter word, say "tile". You change one letter to make a new word, "mile", and then again to "mild", and then "mold", etc. How many iterations would you need in order to use *every* letter of the alphabet (in the above I've...

Can anyone help with this problem?? Children bring their old pumpkins to a tower and compete for an accuracy in hitting a target on the ground. Suppose the tower height is h=8.0m and the bull's eye on the ground is a distance d=3.4 m from the launch point. (neglect air resistance.) If the...

okay I am not sure what the right answer is out of these multiple choices because I am not sure how exactly to use F delta T. A 4.0-N force acts for 3.0 sec on an object. The force suddenly increases to 15 N and acts for one more second. What impulse was imparted by these forces to the...

Hi to everybody I am a student in physics department of M.E.T.U (Middle East Technical University). I am also a member of Metu Physics Socity a group of people want us (From the physics Society) to make a domno show for an international fair opening. We thought to make a show with nearly...

I'm not sure if I'm approaching these problems correctly. Could someone check my work? Steam at 100°C is condensed in 500g of water at 20°C. a. What is the maximum amount of steam that can be condensed in this amount of water? Q[steam] = m[steam] * L[c steam] * (T[f] – T[i]) Q[steam]...

Have you ever heard of that challenge where you have to make each number from four 4s? This list is the best I have been able to come up with, will you help me fill in the gaps? Any solution that is simpler than one here can take its place, for example if you come up with a solution to 33 that...

The question is: Prove suppose A,B and C lie on a line L, with B between A and C, and that D is not on the line L. Prove that angle DBA + angle DBC = 180 this question is obvious. But because its obvious its hard to prove. Say that X = angle DBA and Y = angle DBC therefor cos(X + Y) = -1...

I just started physics, I am in 11th grade and we needed to do a project in some class and I want to do this, but I really need help. I asked my teacher about doing something on magnetic energy (I would have no clue where to begin though…) and she brought up plasmas and doing something on those...

1. calculate the length of the following paths: f(t) = (7, t, t^2) over 1<t<3 the way i was taught in class to calculate the length of a curve is to integrate the magnitude of the velocity, but i can't seem to naturally integrate the magnitude of (0, 1, 2t) similarly for: f(t) =...

I am currently in my second quarter learning the c language. The class is not hard at all, but i want some challenge problems. Are there any goods links?

Given an infinite long cylindrical shell of inner radias a and outer radius b. proof using coulombs law that any point inside the inner radius a, the eletric field will always be zero.

A pilot flies at 140 km/h. The heading is due East for 1 hour,due South for 1 hour, due west for 1 hour and due north for 1 hour. IF a steady wind blows at 60 km/h, how long and at what heading must he fly to return to the start point? The wind is blowing in a northwest direction

An object is place against a compressed spring at the bottom of an air track that slope upward at an angle 30. When the spring is release, find at which position, the object leave the spring? Given: the spring is compressed A, the spring constant is k, m is mass of object, mass of spring is...

Ok, so my college has this BIG "mocktail" competion every year. Each student activity group comes up with a unique mocktail (cocktail without alcohol), that somewhat relates to the organization. The mocktails are then taste tested and voted on. So I'm in chemistry society and I've been told...

I am building this project which involved to PVC pipe chambers to be semi-pressurized (I know PVC isn’t intended for pressure, but I am not talking 200 psi, 40 to 60 psi theoretical MAX, usually around 5 to 10 psi). I have a pretty good depiction of the set up made in ASCII art, but I...

This is probably one of the best FPS out there. Developed by the US Army, highly challenging, requires some strategy, teamwork and it's FREE! And now back to my so-called life...

I'm a senior in high school, and we were just assigned the famous egg drop project... Here are the rules/restrictions/guidelines that our teacher gave us: You will design a container for an egg that will keep the egg from breaking when dropped from a height of approximately 5 meters (we're...

does anyone know how i could go about calculating how much power is needed to move 1,972,080 gallons of water at a constant rate of 25mph or 475,200,000 ft/s?...my friend and i are trying to figure out how to draw up a pool of water that would do this and i don't know how i could go about...

This site was linked at the top of the physics forums website. www.relativitychallenge.com I guess everybody has freedom of speech. Do people just get a kick out of proving Einstein wrong?