Weird Definition and 469 Threads

So I have a couple of cheap <5mw red laser modules. And I also have mirrors. And I'm bored. You can guess what happens next (profit). Some really strange effects that I'd love to know the origin of: 1.) The speckle effect from the laser beams - it doesn't actually matter where your eyes are...

Homework Statement A uniform beam of weight w is inclined at an angle \theta to the horizontal with its upper end supported by a horizontal rope tied to a wall and its lower end resting on a rough floor. (a) If the coefficient of static friction between the beam and floor is \mu_s, determine...

When I was 15, I dropped into a lab in a big city hospital.. The fellow there was doing illegal isotope experiments there... He took me under his wing to teach me some of the strange chemistry things he new... The one that still puzzles me today is his silly little acid/alcohol/p...

[SOLVED] Simple Vector Sum Problem... But My Calculated Angles Weird... Homework Statement A car travels 210 m [N32°E] and then travels 37 m [S51°W]. How far is the car from the origin? Homework Equations Cosine Law. C^2=A^2+B^2-2(A)(B)(CosC) Sine Law. C/CosC=A/CosA The...

[SOLVED] really weird one Homework Statement A small sphere that carries a charge q is whirled in a circle at the end of an insulating string. the angular frequencyy of rotation is omega [w]. What average current does this rotating charge represent? Homework Equations I = dQ/dt; w =...

There is a problem I couldn't figure out , it says : it says that a particle of mass m moves along a straight line and is acted on by a retarding force (one always directed against the motion) F=b*exp(a*v(t)), b, a are constants and v is the velocity. At t=0 it is moving with velocity V...

Hi, I don't know the technical term for this, but you know when you type, the line thing at the end of your text blinks on and off? Whenever I'm typing on an internet page (email, search engine, etc), instead of a line that blinks on and off, there are two highlighted (black) spaces, and...

There is a container full of water with a hole in the bottom. The hole is sealed and fits water-tight around an enclosed cylinder (like a straw sealed at both ends). The cylinder still moves easily vertically and it is inserted in such a way that it protrudes out both the top and bottom of the...

Homework Statement (3) A motorist is approaching a green traffic light with speed v_0 when the light turns to amber. (a) If his reaction time is \tau, during which he makes his decision to stop and applies his foot to the brake, and if the maximum braking deceleration is a, what is the minimum...

Humans oxidize glucose in the presence of oxygen. For each mole of glucose, 686 Kcal are realeased. This is true whether the glucose is oxidized by cellular respiration or burned in air. So why don't humans spontaneusly combust?

Hi there, It is common that angular velocity = radius * rate of change of degree over time, But I read this somewhere, it reads angular vel = normal vector * rate of change of normal vector over time, Can anyone please explain the correlation? Thank you.

Homework Statement Not really a problem, but an analysis question on a lab that I can't figure out. We did an experiment in which we placed a spring scale on a table and attached strings to both sides. The strings went over pulleys and we hung various masses from them. My question is what...

I have got this circuit. http://img225.imageshack.us/img225/4369/circuithf1.jpg Threshold voltage of the n-channel MOSFET is 2Volts. RVAR varies from 0.5k\Omega to 2k\Omega. When I simulate the circuit, I get: http://img132.imageshack.us/img132/2779/simulationuw4.jpg It should go into...

The question is: Write a short paragraph that physical problem modeled by the equation: \frac{\partial{U}}{\partial{t}} = \frac{1}{4}\frac{\partial^2{U}}{\partial^2{x}} -12[U - 8x] Subject to IC: U(x,0) = 3x BCs: U(0,t) =0, u(2,t) = 2t Okay so clearly, the physical problem is...

I've looked everywhere to try to solve this problem and I can't find anything. It is: A conical tank (with vertex down) is 10 feet across the top and 12 feet deep. If water is flowing into the tank at a rateof 10 cubic feet per minute, find the rate of change of the depth of the water when...

Homework Statement Find the limit as x approaches 0 of x^2/(1-cosx). Homework Equations None. The Attempt at a Solution I know from L'Hopital's rule that the limit is 2, but I'm not supposed to use L'Hopital's rule to calculate it. What else can I do here?

Zz's food and wine category and my move reminded me of my bizarre culinary collection. I collect bizarre kitchenware such as a soup tureen that looks like a boar's head, complete with tusks, a chafing dish that looks like a duck, a pewter gravy boat that looks like a rabbit and sits on a...

I wrote my own graphing software, and I thought it had a bug in it, because when I graphed x^x, the curve starts out at (1,1), dips down a little, then rises again to pass through (1,1) as expected, before traveling to the wild blue yonder. It seemed like this function has no range in the...

Over the long weekend I was touring a museum whence I glanced upon a thirtysomething woman and had to look again. There was a tiny arm coming out of her chest. I thought she must be carrying her tiny baby in a receiver (?) shawl wrapped around her, but did not inquire personally. I might have...

Consider integrating sin(t)/t from 0 to infinity via the Taylor expansion method. If you do that then you will get infinite terms in the series which clearly is wrong as that integral equals pi/2. Can anyone tell me why using the Taylor expansion method dosen't work? It always dosen't work when...

Have a strange science based video? Post it here and enjoy the show. Dr. MegaVolt.......a Tesla freak X's 10. More at his site under appearances: http://www.drmegavolt.com/index.html

Please help me out here with this problem: 37. Express the function f(x)=l x l + l x-2 l without using absolute value signs. Okay, I've took a sneak peak at the answer key and it is given in kinda of like piece-wise notation where they have 3 equations and different intervals of x for...

I thought this was really odd. I wonder if they found it by accident or were trying to do this... http://mathworld.wolfram.com/TuppersSelf-ReferentialFormula.html Apparently, the graph of this formula is the formula: graph of formula: the formula...

Isn't \sqrt{2}^{4} equal to 4?? How come when I plug this into my calculator it gives me the number:3.999999999996 , which is very close to 4 but isn't?? Is there something wrong with the settings of my calculator?

are we anywhere near understanding DNA well enough to "program" a new species. say, programing a cell to grow into an animal with specific traits. I know similar things are done to a certain extent with genetically modified foods and animals (or on mosquitoes and flies); I know we know enough...

Huhuhu, this is just sssssoooooo weird... :cry: My friend asked me to copy, and send him some guitar scores. And I agreed. I also told him to give me a USB, since mine is only 512 MB, and the file is approximately 700 MB. So he gave me a 2GB one. I plug it to my computer. Right click on the...

Hi all! I'd like to know what's the latest weird, interesting or simply "ear-catching" news you've heard about the physics world lately! Feel free to share! =)

How did this happen!? Weird picture! So yeah... I was at the bowling alley and someone took this picture: http://a37.ac-images.myspacecdn.com/images01/38/l_81ee85d7d2e5ca216a96f823bb524cfc.jpg" This is NOT photoshopped. I could see an explanation if it were blurred, but the edges of...

Homework Statement This question asks you to evaluate the limit of the following function lim sqrt(9x^2-3x) -3x x-> infinity I did it using 2 methods: 1) lim sqrt(9x^2-3x) -3x x-> infinity = lim x(sqrt(9-3/x)) -3x...

Homework Statement Here are three problems from an exam and I'm not sure i understand the wording... almost like we're supposed to get these wrong. 4. The Boolean expression of the OR between minterm 6 and minterm 7 using variables ABC (A being the MSB and C being the LSB) is {(A)} AB...

Hi all, I have attached a notebook which I am doing a calculation in. For some reason, Mathematica is acting inconsistently. When I run the calculation for the first time, it usually doesn't work. By that I mean I get the output that you can see in the notebook attached. You can that...

Homework Statement Suppose that u(t) is a solution to y'' + p(t)y' + q(t)y = 0 Suppose a second solution has the form y(t) = m(t)u(t) where m(t) is an unknown function of t. Derive a first order linear differential equation for m'(t). Suppose y(t) = e^(2t). Use the method...

Homework Statement To repair a power supply for a stereo amplifier, an electronics technician needs a 100 micro-F capacitor capable of withstanding a potential difference of 90V between its plates. The only available supply is a box of five 100 micro-F capacitors, each having a maximum voltage...

Homework Statement I got this problem in an exam today, and I think I may have the right answer but I don't understand how I'm supposed to know if I do. It's very confusing. Homework Equations If logb (9) = 1.5 and logb (2) = 0.5 what is logb (5throot(36))? The Attempt at a Solution...

Hi i really do not know how to do this. any help is much appreciated. thanks! Homework Statement A projectile is shot out at 45° with respect to the horizon with an initial velocity of Vx = Vy = Vxy. When is the earliest time, t, that the velocity vector makes an angle of 30° with respect to...

Homework Statement A uniform solid disk of radius (r) 6.71 m and mass (m) 38 kg is free to rotate on a frictionless pivot through a point on its rim. If facing the disk, the pivot is on the left side. The disk is then released. What is the speed of the center of mass when the disk reaches a...

It seems to be a law of nature that all things consist of smaller, less complex things: fundamental particles are (comparatively) simple. They react to form atoms, atoms form molecules, molecules form different chemicals, these chemicals also reach with each other to form cells, minerals, etc...

A triple star system consists of two stars each of mass m revoling in the same circular orbit of radius r around a central star of mass M. The two orbiting stars are always at opposite ends of a diameter of the orbit. Derive an expression for the period of the revolution of the stars. I don't...

Mars travels around the sun in 1.88 (earth) years, in an approximately circular orbit with radius 2.28 x 10^8 kilometers determine a)orbital speed of Mars relative to sun b)mass of the sun.. for part a) i did v= 2(pi)(r)/ T which i got 2(3.14)(2.28x10^11 meters)/ 5.93 x10^7 seconds...

Hello: I wanted to know what does the phrase, "When the going gets weird, the weird turn pro" means. Actually I understood the first part of it. But the second part "the weird turn pro" is not clear to me. What does the word "weird" stand for, here? Any answer is appreciated. Thanks in...

Ok, this isn't a particularly hard integral, but for some reason I don't understand why the answer is what it is. Here's the integral (BTW, it's part of a double integral): \int e^{x/y} dx The answer is: ye^{x/y} dy but I don't understand why. Wouldn't it be in the form e^u, with u being x/y...

Here's something really weird. As can be read in Pressley's "Elementary Differential Geometry": Proposition 1.3: Any reparametrization of a regular curve is regular. And 4 pages later: Exemple 1.8: For the parametrization \gamma(t)=(t,t^2) of the parabola y=x², \dot{\gamma} is never 0 so...

Here I am, asking yet another question. :), Gotta keep you guys busy you know. I am just practicing a bunch of integration questions found in a textbook a friend lent me, and I probably don't need to know how to integrate this, but I am interested anyways :)...

Ok the equation: y=(x-1)^2 How come it has a y intercept of (0,1) but the equation does not have a +1 at the end of it?? I thought all y-intercepts are at the end of the vertex-form equation.

what would be the period of cos(2pi*x)*sin(2pi*x)?? calculator is telling me it's 2, but i somehow don't want to believe that also, what would be the period of cos(2pi*m*x)*sin(2pi*m*x)??

carol's age in years, can be expressed by reversing the digits in her father's age, in years. the sum of the digits in each age is 10. the positive difference between carol's age in years, and her fater's age in years___36 a.> b.< c.= d.uncertain In my opinion, there are four pairs...

If you had a pair of celestial rotating in a circle, both of equal mass size. Would it be possible for the planets to have a shared satellite? Thank you for reading, Alex

We are now studying the one space dimension heat equation u_t = u_{xx} [/tex] The fundamental solution is given as: u(t,x)=\int_{-\infty}^{\infty} \frac{1}{2\sqrt{\pi t}}e^{-(x-y)^2/4t}u_0(y)dy I don't understand where the y comes from. The example in this section is: If u_0(x)=1 , the...

Sometimes it seems that my computer generates unwanted internet activity. I know this becuase I can see the activity light on my router blinking. This happens at irregular intervals. And when it happens, my internet connection stops working. I would either have to unplug my internet cable or...

Hey guys; I'm experiencing a really weird problem with my router.. First, my setup: I'm living in the Caribbean so I have to use a goofy ISP. We have a PPPoE DSL connection to them. I then have a Linksys Broadband Firewall Router hooked up to the DSL box, then I have a Linksys Wireless...