Jahanshah Javid

Amazing, Ali A Parsa!

Pool question

Ali A. Parsa, my guess is speed of the swimmer is a function of swimmer's body mass vs the water's (depth or pressure imposed on the swimmer). But exactly how? I'd like to know too. 

Truly impressed with this set of discussions

First, the valid and innocent question by JJ and the helpful responses given is an indication of how this site could be used rather than abused. I am sure that if this were a religious question it would neither be so pleasant nor fruitful. The moral of the story is that like coin we have two sides-negative that scatters us apart and positive that bring us together. I hope one of the take-home lessons of this discussion is that we do our best to be positive.

And, I do not let you scientists off the hook until you explain one question. The question is why does it take me less time to swim the length of the pool from the shallow end of the pool to the deep end than the other way around? I already know that there is not uphill or downhill when we are in the pool! I am gussing that this has something to do with liquid dynamic, a seemingly invisible undercurrent flow from the shallow end toward the deep end that males the swimmer's job easier or someting. Once again I am proud of you scietists and I thank you for letting me pick your brains.  

khody

Dear JJ

I thought you wanted a simple  explanation. Glass is part of solid aka amorphous. I call it a chaotic arrangment versus crystalines that are  very well arranged and organized  with   the geometry of atom structure.

Diamond is a real pure form of solid (made of carbon) is  a crystaline  whereas charcoal also made of carbon is an amorphous type. As you can see the light passes through the diamond and light  is completely absorbed by the charcoal. What is the difference? As Ari mentioned , the light is an electromagnetic force and photon is  a part  of that electromagnetic force. When it hits these surfaces, the photon has only few options, be absorbed (things get warm or hot), reflected or passed  through.

The different color you see in glass is due to impurity and besides Silica there are other earth material  mixed with it. This is all I can tell you, if you are interested you may take Ari advise and read about the optics.

What I gave you as a formual is a do it by yourself thing.

simply multiply your speed by time and divide it by 60. The result gives you the distance you have ran in any unit, km, meter, cm per time.

in that case watch this and pretend you did :o)

//www.youtube.com/watch?v=m1vkXxn65ec

Fat chance

Monda, I haven't smoked anything in three months. I don't know any suppliers. Chihuahua aint California or Amsterdam. It would have been so great if I had some right now :)

Your blog topic Sounds promising :o)

But I only learned that you're walking/running 4.6 (Foaad without calculator?!) which is Awesome especially if you're having fun at it.  I was going to suggest what Azarin suggested, but not all treadmills have those dial thingies.  JJ you're working out 5 miles a day and you still have energy to wonder about the physical properties of glass?!  I'd like to smoke some of what you had tonight :o)

Transparent Green

Ari... I believe you :)

Think Green movement, JJ

Other transparent materials

Thanks for the link to transparent aluminum Ari. Absolutely fascinating. There were also links to other transparent materials one would never expect. I can't say I fully understand what's going on, but I've learned a lot.

I'm looking at a window right now and still thinking... how the hell can I see through it, but not the wall! :)))

Getting there

Thanks for the googled info Khar. I am getting the general idea...

JJ, can't be done without wave concept

Khar, "Glass is a non-crystalline material..." while true does not explain transparency. Here's the perfect crystaline structure of quartz, which people use if they want tranparency all the way from infrared wavelengths to ultraviolet. Here's is a transmittance graph for quartz. The quote you cite is correct as far as glass absorption characteristics. But to explain transparency it is not enough to say the atom doesn't absorb the light that hits it, you also have to explain why the light doesn't change direction (scatter) after it hits the atom. For that you need wave theory.

not rocket science

it is going to blow your mind to know that the glass you were looking through used to be sand before the molecular arrangements were altered(packing in the solid state) by melting and addition of more stuff to it.

Seriously, depending on the crystal packing of a solid, the folowing can happen (//science.howstuffworks.com/question404.htm):

* An electron absorbs the energy of the photon and transforms it (usually into heat)

* An electron absorbs the energy of the photon and stores it (this can result in luminescence, which is called fluorescence if the electron stores the energy for a short time and phosphorescence if it stores it for long time)

* An electron absorbs the energy of the photon and sends it back out the way it came in (reflection)

* An electron cannot absorb the energy of the photon, in which case the photon continues on its path (transmitted)

------------------------------------

you have the answers for miles from several people, but next time look down at one of the dials on your treadmill which tells you how many miles you have walked.

Thanks you smart people

masoudA: I don't think it has to do with color. If you look at glass from the side it has a greenish color and not "invisible". So the viewing angle makes a difference.

bajenaghe naghi: For sake of argument, let's say glass is a liquid. Then why can we see through some some liquids and not others? Liquidity does not seem to be the important factor in "invisibility".

Azarin Sadegh: Good suggestion. Figuring out functions on a gadget are just as confusing to me as a simple math problem :)

Darius: I see math/physics formulas and I want to run to zee hills! As for photons and absorbing light: interesting, but still question remains why glass is "visible" when you look at it sideways, but not straight on.

Khar: Thanks for the calculations. It's now official. I'm dumber than a donkey! :D
And yes, I am running and walking 4.66 miles a day. Proof is in my nephew Robert's upcoming video.

Ari Siletz: I'm not sure I understand. Actually, I don't understand at all! Imagine you're talking to a 10-year-old (I didn't want to say five!). And my follow-up question would be, if a solid such as glass can appear invisible, can't the molecules of other solids be rearranged so that they would become see-though as well. I bet some defense contractors are working on that in order to make soldiers and weapons invisible in combat (other than through anti-radar stealth technology).

Googled this one..

"The first thing you need to know is what determines if an object is transparent (transmits visible light) or not.

Visible light is part of the elctromagnetic spectrum so this means it has some inherant energy. A convinient way of measuring that energy is with a unit called the electron-volt or eV. An electron volt is the energy gained by an electron accelerating through a potential difference of 1 volt. Visible light is the part of the electromagnetic spectrum between 1.7 and 3.1 eV.

In order for something to be transparent to visible light, the atoms in the material must not interfere with the transmission of that energy. This interference is most often accomplished when the material absorbs the energy from the light and uses it to excite one of it's electrons to a higher energy level.

The determining factor in if the material will absorb the light is a property known as the energy gap (Eg). Basically this is the amount of energy needed to excite a valence electron (an electron on the outermost unfilled shell of an atom) to the conduction state. Einstein showed that energy can only be absorbed in discrete packets called quanta (this is where the term quantum mechanics comes from), which means there will be some set value of energy at which point the material will start absorbing all energies equal to or greater than that value (again, this is called the optical gap).

This leads us to why glass is transparent.

Glass is a non-crystalline material, which means rather than having a regular and repeated alignment of its atoms it has a disordered random atomic structure. This is accomplished by cooling melted glass before the atoms can arrange themselves in a nice, neat way. In essence you must freeze-in the disordered liquid atomic structure. So glass is a non-crystalline solid and because of this, it's bonding is very strong and directional (highly covalent bonding). Since it is electrons that will absorb incoming light energy, there must be electrons available to do this. In glass there are very few free electrons for energy absorption so the optical gap is very high (greater than 3.1 eV). As a result light of energy less than the optical gap (in this case visible light) will pass through. It should be noted this is why glass is also a good electrical insulator.

There are some who will claim because glass has a "frozen-in" liquid structure that with time it will slowly flow like a liquid, but this is not true. If glass could flow that way it would mean the bonding was very weak - and as you've just found out that would mean it couldn't be transparent! "

The simplest answer!

Results : Over a 4 month time course, 22 cycles of growth and dilution of the glasses can be used to select 2 thermotolerant variants of M. anisopliae. Both variants displayed robust growth at 35.5°C, whereas only one was able to grow at 37°C. Insect bioassays using Melanoplus sanguinipes (grasshoppers/Green Movement) were also performed to determine if thermotolerant variants of M. anisopliae retained entomopathogenicity. Assays confirmed that thermotolerant variants were, indeed, entomopathogenic, albeit with complex alterations in virulence parameters such as lethal dose responses (LD50) and median survival times (ST50)... (makes sense, doesn't it?) :0)

As for your Math question, please let me know if you would like me to further elaborate!!! LOL!

Just kidding JJ Jaan... I'm glad you already got your answers from the smart people out here... They are impressive...

PS. Running almost 5 miles a day? That's fantastic ... :-)

Be well...

First things first, JJ

1. Light can be regarded as a wave, similar to water waves.

2. Waves heights add algebraically, so that if at a point in the swimming pool a plus (peak, crest) of one wave falls on a minus (valley, trough) of another wave the result is no wave height at all (still water level as though there were no waves at that particular point in the pool).   

If you are familiar with these ideas, let me know and we'll take it from there. It will take a few back and forths, and by the time we're done you will be asking why somethings are not transparent.

Most of the info will come from the classic text  Optics by Eugene Hecht.

Here's another way...

5/60 x 3.5= .291 x 4 =1.166

10/60 x 5=  .833  x 2 =1.666

10/60 x 5.5= .916 x 2=1.833

Walking /day= 1.166 miles

Running /day= 3.499 Miles

Total walking & running= 4.665 miles /day (to be exact)

Never mind why the glass is clear, now the question is; do you really  run/walk 5 miles a day? Awesome, good for you man! ;-)

distance= speed

distance= speed *time

this is the formula you need to use,simply plug in the number

d=speed/mile * minute * 1hour/60 minutes

simplify that and the answer is

d=(speed *minute  ) /60 =        miles

The light contain photons, some capable of absorbing it(flourescent) and some simply can't and let is passes through.

The Silica the main ingridient and some other elements in glass

at high temperature melt  and after cooling create a bond that holds it together without falling apart( amazing, almost a liquid).

What if you look down...

Dear JJ,

On the trademils' screen, if you look down, there is a spot where it shows the total miles you've run...and I've seen this little feature in almost every trademil..:-))  Plus, that number is very precise, and it would tell you the exact distance you've walked or run each time. 

JJ jan

Just to make this even harder, I have heard that glass is not solid at all! It is liquid with its molecules moving ever so slowly, faster in heat and much slower in cold.

I have also heard that when the molecules of something are very closely bonded together so that no light can pass through them they are said to be solid. If molecules are loosely bonded together so light can pass through them then they are either liquid or gas.

Has nothing with where the atoms are

Color of objects or lack thereof - has everything to do with which elements (remember table of elements?) are mixed together at what proportions.   I was always amazed in chem lab class when we added a bit of copper to clear acid sulfuric and got a beautiful blue color salt so4cu2 - or was it something else?  lol

Not quite

Thanks SamSamIIII, but I'm not satisfied. And I don't think your daughter is either. Water molecules are more flexible, but not glass.

You're God

Thanks Foaad (admin). Without a calculator, huh? I'm so damn impressed. I really wish I could understand math. Pure logic :)

Bizzar

Since just a few hours ago I was asked the exact same question by my daughter who happened to have a class on subject of atoms and asked as why water is colorless when just like every thing else it,s made up of the same atoms that stones or metals are made up . Well my short answer to her from memory is "rigidity & inflexibility" of solids vs liquids & gasses and transparent glasses . the set up and order of molecules or (atoms?)in liquids & gases is much weaker and less orderly as with the molecule bonds in solids in which light can pass thru easier . weired question twice in a day :).hope I made some sense.

Cheers!!!

Path of Kiaan Resurrection of True Iran Hoisting Drafshe Kaviaan //iranianidentity.blogspot.com //www.youtube.com/user/samsamsia

the math question: with no calculator

5 minutes is one twelfth of an hour, there are 12 different 5 minute periods in one hour. 10 minutes is one sixths of an hour. You also repeat your 3.5 m/h walk once so we can just multiply that by 2 in the first term below.

T = (1/12 x 3.5 x 2) + (1/6 x 5) + (1/6 x 5.5)

reducing a bit

= (1/6 x 3.5) + (1/6 x 5) + (1/6 x 5.5)

factoring out 1/6

= 1/6 x ( 3.5 + 5 + 5.5 )
= 1/6 x ( 14 )
= 14/6
= 12/6 + 2/6
= 2 miles and one third of a mile
~ 2.33 miles

That's just morning. Double that for the whole day:

~ 4.66 miles