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Why does the colour black heat faster than white?

  1. May 2, 2004 #1
    I am required to ask questions as part of my physics assignment at school. Im in Yr 11 physics btw. If some people can please answer these that would be great. Before anyone says i should know some of these or that i could find out by surfing the internet, i know that i canm but none the less i would stil be required to ask questions to a person/s about physics.

    Thanks in advance.


    1)Why does the colour black heat faster than white?

    2)How and why are rainbows formed?

    3)Why does a diamond sparkle?

    4)why does water cool down so much slower than it heats up?

    5)What are Newton's three laws?

    6)Why can a person lie on a bed of nails and not be injured?

    7)What is a Black hole?

    8)When you look into water why do objects appear to be in a different spot than if you were looking from underwater?

    9)Is there any truth in the statement "Red is the fastest color"?

    10)What are potential and kinetic energy?
     
  2. jcsd
  3. May 2, 2004 #2

    HallsofIvy

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    Okay, you were required to ask questions. Are you required to get any answers?
     
  4. May 3, 2004 #3
    yes, i wouldnt bother posting them if u didnt want answers
     
  5. May 3, 2004 #4

    HallsofIvy

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    1)Why does the colour black heat faster than white?
    Black absorbs all colors of light, white reflects them: light is energy, i.e. heat.

    2)How and why are rainbows formed?
    Different colors of light are refracted at different angles by drops of water in the air. In order to see the same color, the light must go at the same angle from the sun to your eye which is why a rainbow is a circular arc.

    3)Why does a diamond sparkle?
    Same answer, really. Different colors of light are refracted at different angles. Diamond has a very high refractive index so it is much more apparent than with glass or crystal.

    4)why does water cool down so much slower than it heats up?
    I didn't know it did! If you take two equal glasses of water, one at, say, 10 degrees above room temperature, the other at 10 degrees below room temperature, they should go to room temperature in the same time.

    5)What are Newton's three laws?
    I got those from http://csep10.phys.utk.edu/astr161/lect/history/newton3laws.html and I got that url by going to "google.com" and entering "Newton's Laws". If you are learning to use the internet to answer physics questions, I recommend you become familiar with google!

    6)Why can a person lie on a bed of nails and not be injured?
    I, personally, wouldn't want to do it but if there are enough nails, the weight of your body is spread across all the nails so there is only a little force on each one. Think of it this way: if you put the nails right up against one another, you would have a flat metal surface!

    7)What is a Black hole?
    A mass so concentrated (we are talking about the mass of the sun squeezed into a few cubic millimeters here) that its "escape velocity" is greater than the speed of light.

    8)When you look into water why do objects appear to be in a different spot than if you were looking from underwater?
    Refraction again. When the light wave passes from the water to the air, on its way to your eye, the change in speed causes it to bend at an angle. Of course, your eye and brain only know the final angle of the light so you "see" the object as if it were on that line.

    9)Is there any truth in the statement "Red is the fastest color"?
    I don't think there is any sense in it!
     
  6. May 3, 2004 #5

    Doc Al

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    I'll just add a few notes to Halls' answers.

    That especially high refractive index, coupled with the way the diamond is cut, cause much total internal reflection within the diamond: the light bounces around inside, until it finds a straight path out. (In ordinary glass, the light would leak out the sides instead of reflecting back out where it came in.)
    Think of it this way: Would a person want to lie on a bed of nails with only one nail?
    Only in the sense that the refractive index of many transparent substances (like glass or water) depends on the wavelength. And red light generally has a lower index of refraction than blue light. Which means that red light does go faster in glass or water.
     
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