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  #41  
Old Tuesday, June 29, 2010
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thank you sir

The aerodynamic V shape reduces the air resistance, allowing the geese to cover longer distances.
why sound travels in the form of cone (Vshaped) because in air this is the path which provides least resistance.
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  #42  
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yp umair is right........Q was asked bout the pattern of flights not regarding thier shape....V shaped pattern of flights is usually seen in aircrafts engaged in common missions and in airshows.In world war 2 V pattern of flights was used to form combt boxes to efectively hit enemy lines.
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Quote:
Originally Posted by siraj narejo View Post
thank you sir

The aerodynamic V shape reduces the air resistance, allowing the geese to cover longer distances.
why sound travels in the form of cone (Vshaped) because in air this is the path which provides least resistance.
dear siraj...that's exactly my point...your argument holds true about the geese structure..for example they have a large span for wings so that uplift is more....but flying in a V pattern will not reduce their individual drag...they will all face the same resistance from the air..

similarly a bullet is shaped (somewhat like a V) or a cone....because it's structure will then draw lesser drag from the air!!!..

let's assume if the planes have an aerodynamic shape (F-16 for example) it is so designed to reduce the drag on it...so the drag will only increase with speed and will not be affected whether the plane flies in a V formation or column or row formation!!! the drag remains the same at the same speed...

yes in a box formation you can say, that the exhaust fumes of the preceding planes will increase the drag for those following it....
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  #44  
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why some detergents include live microbes?

Some biological organisms help break down the organic compounds. For example, in sewerage treatment plants, we often determine BOD (Biochemical oxygen Demand) to sustain the biological organisms.

if i drop from the tower of pisa a kilo of wool and also a kilo of iron. which will hit the land first? first think then reply?

If you donot neglect the air resistance, a kilo of iron would drop fairly quickly than the kilo of wool.

what should be increased to make float a drowning body? (its length, width or height) and why?

Its length and width both. By floating I presume you mean float over the surface of water and not 'suspended'. For suspension, height must also be considered.

if we allow DC current to flow from electric wires what will happen? (normally AC current flows through them)

Voltage transformation (in transformers that we often see) would not be possible. This is another question, why we need transformation of volatege. Power is the multiple of voltage and current, and we require a specific power rating for operation of any equipment. Higher current generates higher losses in the wire there, for transmission, we prefer higher voltages (read about high tension power lines). But at user end, we need to tone down this voltage and for that we need transformers.
P.S: There are other reasons for using AC electricity too!

manual qulfi makers add salt to ice? why do they do this?

Adding any impurity lowers the melting point. For example, adding salt to ice would drag its melting point lower. Imagine ice is at -3 degree C and its melting point is 0 C (assumping its distilled or deionized water). Now, if you add salt, it would drag the melting point to -1 C which would be reached sooner than 0 C as the temperature of ice increases. And we all know why we would like to have melting quicker when making ice, right?

how X rays can be used to check diamond purity? how

A Phenomenon prevalent in industry called X-Ray Diffraction! In principle, X-rays bounce off the lattice of the crystal of diamond and are recorded. However, any change in lattice (caused by any impurity) would be readily observed as the intensity of reflected wave decreases.

can we increase the speed of light? if yes then how .plz think then reply(i dont need the ans. NO)

No. I'll tell you something interesting. Suppose you are travelling on a moving car and throw a ball outside in the direction you are moving. The total speed of ball will be the speed of your car AND the speed of light, right? For light, it doesn't work like this as proven by the theory of relativity. VERY INTERESTING. I strongly suggest you study theory of relativity to get some insight into this phenomenon.

why can we not cut the diamonds?(normaly)

Diamond is the hardest NATURALLY occuring material followed by boron nitrides and boron carbides. However, artificial material like diamond nano rods are available which are harder than diamonds.
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  #45  
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Quote:
Originally Posted by RAO RAMEEZ View Post
I wanna add something that testosterone is one the causes of baldness and especially Pattern baldness in Men. ( MEDICAL PHYSIOLOGY BY GUYTON)
What's pattern baldness??? It is fall of hair on the dorsal side of forehead..it is also an assurity that the person is sexually sound.
No DHT is not the single hormone, Insulin is another culpirt causing baldness....
Go through topic polycystic ovarian syndrome if your Guyton has it.................
Mechanism
high insulin level causes decrease in SHBG a globulin that binds testosterone and prevents its conversion to DHT because only free testosterone is converted in DHT.So when SHBG is low conversly DHT is high in body causing more hair loss.
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remaining questions to be answered!

why hot soup/food is more tasty than cold one?

why bread become green then black? why do it not turn black then green?

why wax shrink on heat? (opposite to normal things)

why fire does not work on the threads of asbestos?

how infra red rays help to read from burnt papers?

can we increase the speed of light? if yes then how .plz think then reply( i dont need the ans. NO)
i am not fully satisfied with earlier answer.
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  #47  
Old Wednesday, June 30, 2010
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Quote:
Originally Posted by Farid_Asclepius View Post
No DHT is not the single hormone, Insulin is another culpirt causing baldness....
Go through topic polycystic ovarian syndrome if your Guyton has it.................
Mechanism
high insulin level causes decrease in SHBG a globulin that binds testosterone and prevents its conversion to DHT because only free testosterone is converted in DHT.So when SHBG is low conversly DHT is high in body causing more hair loss.
bro i had written "one of the causes" not "only cause of baldness"....there can be hundreds....especially i have written that in concern with sex..i.e maleness.
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  #48  
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some new questions

why honey is never spoiled? scientists have found it edible in the pyramids along with mummies!

why do fans have 3 wings?

why do we not use milk with fish/eno?
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Originally Posted by siraj narejo View Post
some new questions

why honey is never spoiled? scientists have found it edible in the pyramids along with mummies!

why do fans have 3 wings?

why do we not use milk with fish/eno?

Why do fans have 3 wings?

Perhaps, the 3 wings will cut more air and hence force the air to flow downwards, meaning we get more air with three wings. Four may make it more heavy (consuming more energy) while 2 may reduce the amount of air forced downwards.

why does not honey get spoiled?

Liquid honey does not spoil. Because of its high sugar concentration, it kills bacteria by osmotic lysis. Natural airborne yeasts cannot become active in it because the moisture content is too low. Natural, raw honey varies from 14% to 18% moisture content. As long as the moisture content remains under 18%, virtually no organism can successfully multiply to significant amounts in honey. (wikipedia)
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  #50  
Old Saturday, July 31, 2010
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Lightbulb Why leaves change color in the fall?

WHY DO LEAVES CHANGE COLOR IN THE FALL?

Plants make their own food. They take water from the ground through their roots. They take a gas called carbon dioxide from the air. They turn water and carbon dioxide into food and oxygen. Oxygen is a gas in the air that we need to breathe.

Plants make their food using sunlight and something called chlorophyll. Chlorophyll gives leaves their green color.

Winter days are short and dry. Many plants stop making food in the fall. The chlorophyll goes away. Then we can see orange and yellow colors. These colors were in the leaves all summer, but the green covered them up.

Some leaves turn red. This color is made in the fall, from food trapped in the leaves. Brown colors are also made in the fall. They come from wastes left in the leaves.
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