What is Green: Definition and 306 Discussions

Green is the color between blue and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495–570 nm. In subtractive color systems, used in painting and color printing, it is created by a combination of yellow and cyan; in the RGB color model, used on television and computer screens, it is one of the additive primary colors, along with red and blue, which are mixed in different combinations to create all other colors. By far the largest contributor to green in nature is chlorophyll, the chemical by which plants photosynthesize and convert sunlight into chemical energy. Many creatures have adapted to their green environments by taking on a green hue themselves as camouflage. Several minerals have a green color, including the emerald, which is colored green by its chromium content.
During post-classical and early modern Europe, green was the color commonly associated with wealth, merchants, bankers and the gentry, while red was reserved for the nobility. For this reason, the costume of the Mona Lisa by Leonardo da Vinci and the benches in the British House of Commons are green while those in the House of Lords are red. It also has a long historical tradition as the color of Ireland and of Gaelic culture. It is the historic color of Islam, representing the lush vegetation of Paradise. It was the color of the banner of Muhammad, and is found in the flags of nearly all Islamic countries.In surveys made in American, European, and Islamic countries, green is the color most commonly associated with nature, life, health, youth, spring, hope, and envy. In the European Union and the United States, green is also sometimes associated with toxicity and poor health, but in China and most of Asia, its associations are very positive, as the symbol of fertility and happiness. Because of its association with nature, it is the color of the environmental movement. Political groups advocating environmental protection and social justice describe themselves as part of the Green movement, some naming themselves Green parties. This has led to similar campaigns in advertising, as companies have sold green, or environmentally friendly, products. Green is also the traditional color of safety and permission; a green light means go ahead, a green card permits permanent residence in the United States.

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  1. N

    What Is the Expert Golfer's Ideal Single Stroke on the Green?

    A novice golfer on the green takes three strokes to sink the ball. The successive displacements are 4.00 m to the north, 2.00 m northeast, and 1.00 m at 30.0 degrees west of south. Starting at the same initial point, an expert golfer could make the hole in what single displacement? I drew...
  2. L

    Green power project - little hydrogen cruiser

    I bought this stand up scooter for $850. It's made by a company called http://goped.com" . It can go upto 20mph and I weigh 142lbs. But the problem is, as with all electric scooters is they get low range. Mine get's about 10 miles and it runs on stock SLA batteries packs. Picture...
  3. T

    Tom Green says I'm wrong about Quantum Physics

    Heads up . . . I have not formally studied quantum physics, but I do read about it and watch videos by some of the greats. I understand the conflict between the "micro" and "macro" physics, but I do no understand most of the details of quantum physics. Now, Tom Green enters the picture. He...
  4. N

    Have You Bookmarked the New Alex Stef Math Resource Page?

    Those familiar with Alex Stef's page with the list of online lecture notes on mathematics and related topics may want to update their bookmarks. This is new site: http://users.ictp.it/~stefanov/mylist.html Those who are coming across this site for the first time may want to bookmark it...
  5. T

    Hamiltonian and Green functions.

    Let be the 1-D Hamiltonian: \hat H = -\hat D ^{2} + V(\hat x) (1) and its associated 'Green function' so: -D^{2} G(x,s)+V(x)G(x,s)=\delta (x-s) (2) then my question is if there is a relationship between: Tr[exp(-a\hat H ) ] and Det[1-aG] (3) where a >0 and 'G' is the...
  6. ZapperZ

    FINAL VOTE Photo Contest - Green With Envy

    This is the dreaded final round. It will be a difficult one. Good luck to everyone! Please vote for the picture that best represents our theme: the color GREEN. 1. SpaceTiger http://www.astroskwurl.net/PF/Green.jpg 2. Janus...
  7. ZapperZ

    VOTE Photo Contest Group 2 - Green With Envy

    This is the 2nd group in this contest. Please vote for the photo that best represents our theme for this week, which is the color GREEN. 1. Moonbear http://img59.imageshack.us/img59/3446/greenhi9.jpg 2. Integral http://home.comcast.net/~Integral50/Photo_contest/HPIM1001a.JPG 3...
  8. ZapperZ

    VOTE Photo Contest Group 1 - Green With Envy

    This is certainly going to be another difficult contest to vote on, even for the first round. You have one vote to cast in each group. Please vote for the picture that best represents our theme, which is the color GREEN. 1. SpaceTiger http://www.astroskwurl.net/PF/Green.jpg 2...
  9. ZapperZ

    PF PHOTO CONTEST - Green With Envy (3/17-3/23)

    Green With Envy Just in time for St. Patrick's Day this weekend, our theme for this week will be the color GREEN. Your picture must have the color green as the dominant color in the picture. Good luck of the Irish. Contest Rules: 1. Any digital photo or digitally-scanned photo...
  10. M

    Line Integral + Green Theorem problems

    Question 1) Integrate y^2 dx + zx dy + dz, along the circle x^2 + y^2 – 2y = 0 to (1, 1, 0) I am not sure how to begin on this problem. Would it be beneficial to convert to polar coordinates? The thing that is throwing me off is the fact that the circle’s equation is not the normal circle...
  11. T

    Finding a Green Function for y''+1/24y=f(x) with Bounded Conditions | Math Help

    Hey, I am trying to find a GF for the function: y''+\frac{1}{24}y=f(x) The function is bounded by: y(0)=y(\pi)=0 I have followed a math textbook that goes through the exact process for the function: y''+k^2y=f(x) and have found a nice looking general solution...
  12. S

    How to Find Green Function for y'' + 1/4y = f(x) with Boundary Conditions?

    Homework Statement Hey folks, I need to find a Green function for the equation: y'' +1/4y = f(x) With boundary conditions y(0)=y(pi) = 0 The Attempt at a Solution I tried some combination of solutions that look like sin(kx) and sin(k-pi) and looked at the strum liouville...
  13. I

    Mystery of the Bright Green Meteor: Is it Common?

    I saw a bright green meteor yesterday. What would cause a meteor to be bright green? Is this common?
  14. P

    Photosynthesis occurs in all plant life and makes plant green

    Photosynthesis occurs in all plant life and is responsible for making them green. Why are not all plant life green. I.e. flowers can be yellow, red and some leaves too like the leaves of Poinsettia. Is the reason because no photosynthesis goes on in them? Or is something else more dominant...
  15. Ivan Seeking

    News Is GM Making a Big Move Towards Going Green?

    http://www.detnews.com/apps/pbcs.dll/article?AID=/20061129/UPDATE/611290443
  16. K

    What're the condition for a green function to exist?

    What're the condition for a "green function to exist? That's my question,let's suppose i define the functions: G(x,s)=exp(x-s)^{2} and R(x,s)=(e^{st}-1)^{-1} My question is, could G and R satisfy the condition (for a linear operator L) LG(x,s)=\delta (x-s) ?. My interest lies...
  17. R

    Need to find Green Function to solve ODE

    Hi, I have a basic ODE: y''(x)+\frac{1}{4}y'(x)=f(x) on 0<x<L With Boundary conditions: y(0)=y(L)=0 For which I would like to construct a Green Function. Rather than just plain ask for help, I'll show you what I've been thinking and maybe someone wiser can help/correct me...
  18. L

    Quick green function question

    I am demonstrating the mean value theorem, which says that for charge-free space the value of the electrostatic potential at any point is equal to the average of the potential over the surface of any sphere centered on that point. I have already found one way to do this, but would also like to...
  19. C

    Green Pea Discharge: How Much Charge Can It Hold?

    I don't have a clue on where to start this as i don't know what other figures to use. Dry air will break down and generate a spark if the electric field exceeds 3x106N/C. How much charge could be packed onto a green pea (diameter 0.75cm) before the pea spontaneously discharges?
  20. DaveC426913

    Treating Green Algae in a Goldfish Pond: Visibility ~2 Inches

    How do I treat a goldfish pond green with algae? Visibility is ~2 inches. It's not the wall coating I'm concerned about, it's the water itself. I know how I'd treat it indoors - with a scraper and a water change, but that won't work in a pond. (Well, I suppose a water change would help...)...
  21. J

    Green Functions: Finding Solutions for Equations of All Types & Dimensions

    I need a list of Green functions, for different types of equations and dimensions. I have tried to use google but with no success.
  22. Ivan Seeking

    FDA Denies Petition on Health Claims of Green Tea

    http://www.hsrmagazine.com/hotnews/65h101448772375.html
  23. DaveC426913

    Is Your Aura a Reflection of Your Personality?

    "[URL http://www.davesbrain.ca/aura/index.php I am so pleased. My greatest PHP app yet! Exceeded 4 kilo-users! Your "aura" is your personality type, determined by a questionnaire (think Meyers-Briggs test). Loads of info about what type of person you are.
  24. D

    Physics Can a career in physics help solve environmental issues?

    Are there any fields of physics that one can go into after getting a masters or a phd that merge together experimental or theoretical physics and directly tackling environmental problems. The only thing I could think of is fusion research, which could eventually lead to cleaner energy. More...
  25. Integral

    Green Laser Beam: 10W Power & 1064nm | Home.comcast.net

    A few months back there was a thread with a pic of a visible beam being emitted by a green laser pointer. There was some discussion as to whether or not it was a photochop. Here is a pic I took of "my" green beam laser. I am not at liberty to say a lot about this laser, but it is 1064nm and on...
  26. T

    Need Help Solving Physics Problem Regarding Green Light

    hey so I'm having a lot of trouble on this section of physics. the question I'm on is: Green light (546nm) strikes a single slit at normal incidence. what width slit will produce a central maximum that is 2.3 cm wide on a screen 1.42m from the slit? I've been trying to manipulate...
  27. D

    Molar Mass & pKa of Bromcresol Green - AP Chem Pre-Lab

    Hi everyone. I'm doing a pre-lab for AP chem class. I forgot to check for specific data I need in the Merck. I was wondering whether anyone out there has the molar mass value and pKa of the indicator bromcresol green. Any help would be great. Thanks in advance.
  28. zoobyshoe

    Green Envelopes: Unused & Forgotten?

    Does anyone use the green envelopes at the left of threads to make decisions about what to open? I never do, and often forget they're there. When I happen to notice them I have to go to the bottom and refresh my memory of what each means.
  29. N

    Green function for bilocal operatos?

    Dear PF, Could you tell me what is Green function for bilocal operators? As I understand from its form G(x1y1, x2y2,...)... now the pairs of XY are considered as points instead of single X points as in normal Green function G(x1,x2,x3...). So What do we need it for? Or can it be decomposed...
  30. L

    Understanding Green Stool: Causes and Meaning

    I know you guys aren't exactly biologist but,what does it mean if you get off the toilet and you see green stool?
  31. R

    Uncovering the Mystery of Why the Sky Isn't Green

    The sky is blue because the white light is diffused by the light particles, which scatter out the blue end of the spectrum, hense a blue sky. In the afternoon, it is often red or orange, because the light has to travel much longer through the atmosphere, scattering out the red end of the...
  32. R

    Green Functions: Solving Inhomog. ODE's with Ease

    What is the advantage of using Green Functions to solve inhomog. ODE's?
  33. C

    What is the speed of the car when it overtakes the truck and how far does it travel in 10 seconds?

    At the instant the traffic light turns green, an automobile starts with a constant acceleration a_{x} of 6.0 \frac{ft}{sec^{2}} . At the same instant, a truck traveling with a constant speed of 30 \frac{ft}{sec} , overtakes and passes the automobile. (a) How far beyond the starting point...
  34. A

    Can Leaving Green Tea Out Overnight Poison You?

    i've heard that if you leave green tea out overnight, it'll become poisonious. is that true?
  35. M

    Green Tea Health Benefits: Is There Proof?

    has science found any documented proof that drinking green tea every day has health benefits for you? If so what are they? ~Kitty
  36. T

    Red Balls, Green Balls and Expectations

    Suppose r red balls and g green balls are mapped randomly among b bins. Calculate the expected number of bins where red balls are in majority. My attempt, Let x_ijk = 1 (when kth bin contains i red balls and j green balls) = 0 otherwise Then, F = \sum_{k=1}^{b} \sum_{i=1}^{r}...
  37. E

    Green similar problem

    i would like to find an operator G(x,s)=G(s,x) so LGx,s)=H(x-s) with H(x) Heaviside,s step function,and its inverse problem that,s it given a function G(x,s) obtain the Operator L,my question is how are the functions, a(x) b(x) and c(x9 related to the values of G(x,s) and its derivatives...
  38. F

    Green Wing Obsession: BBCA Taking Over My TV Time

    I am addicted to the show "Green Wing" on BBC. Anyone else watch this? I love BBCA. What TV I do watch BBCA takes up about 80% of that time.
  39. P

    Is the moon made of green cheese?

    A recent spate of now closed threads gave me an irriisistable impulse to ask this question...
  40. S

    Natural Green Eyes: Close-Up Pics

    Can you please post pictures (Preferrably close-ups but they don't have to be) of natural (Not man-made) green eyes in this thread (I need them for a school project I am doing on genetics) and I am having trouble finding close-ups of ones that I know are natural) (If the pictures look really...
  41. ShawnD

    What is the Color of Green Copper?

    Pure copper metal is orange (or pink after being anodized), copper hydroxide is blue, copper oxide is black. So then why is the statue of liberty green?
  42. E

    Red light to green light homework

    What speed would a vehical have to travel in order to red traffic light into a green traffic light? i know that green light has wavelength of 5.40x10^-7 m frequency of 5.56x10^14 hz red light has wavelength of 6.60x10^-7 m frequency...
  43. N

    Green fuktion on the wave operator in 1 dimension

    I have a Homework here I'm trying to solve like the last 3-4 hours but somehow I'm stuck so I ask you guys for help: They gave me the Green Function like this: http://idefix.physik.uni-freiburg.de/~aufgabe/THEO204/theo9/img50.png with...
  44. C

    What Color Are the Stairs in a Green House?

    Ok, a man lives in a one story house with no poarch or basement, If the walls are green, the coach is green, the lamp is green and the ceiling is green what color are the stairs?
  45. O

    News Should Green Party Voters Consider Voting for Kerry Instead?

    Please please don't do it. Hear me out... Yes, our two-party system is a heavy cross to bear, and I would love to do away with it. It's a real shame that we are reduced to chosing between the lesser of two evils, but that is the reality of the situation we have. Let's say you have 11...
  46. M

    Mysterious Green Stars in Patriotic Photos

    in some photos, mixed among the red white and blue stars, are green stars. Any idea what causes this?
  47. E

    Why Plants are Green: A Physical Argument

    from a physical argument if plantes were black they would absorbe more energy from the sun then..why clorophile is green anbd why the plants are green?..
  48. E

    Green inverse problem in Differential equation

    Let be L(Y)=a0(x)D^2y+a1(x)Dy+a2(x) with the boundary conditions Y(a)=c and Y(b)=d then we could construct the Green function L(y)G(x,s)=d(x-s) then my question is if given the G(x,s) we could construct the L(y) operator considering is a second order differential equation.
  49. L

    Green function and the boundary conditions

    Hello there, I am glad that I found this forum. Because I have a little bit trouble with theoretical physics. :yuck: The problem is the Green function in theoretical electrodynamic. I try to understand the difference between the Dirichlet Condition and the Neumann Condition. I...
  50. E

    What Causes Rivers and Lakes to Appear Green in Glaciated Upland Regions?

    In this glaciated upland region why is the the river or lake a green colour? Me thinks that it is obviously to do with the sediment on the bed of the lake. Perhaps it is a chalk bed or a solution lake?
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