Science & Mathematics - 21 January 2007

There is this famous paradox of two twins: one goes off to space in a spaceship at a very high speed and the other twin stays back.
Apparently, when the twin returns to Earth she will be younger than her sis who stayed back in Earth.
How can this be...... the Earth twin will see her sis's time slow down. Similarly, the traveling twim will see her sis in Earth has slower time....
So whats the paradox here?
And i ve heard that its the traveling twins accelaration when turning back to return to Earth is the most important point here!
please kindly explain this paradox to me....

2007-01-21 23:59:02 · 9 answers · asked by sh 1 in Astronomy & Space

Single crystals of metals will conduct electricity equally well in all directions but a single crystal of graphite will only conduct in one direction. Could anyone suggest a possible explanation for this in terms of the structures of the materials?

Thank you

2007-01-21 23:57:16 · 3 answers · asked by yummygummybear2006 1 in Chemistry

i have to make a report on any topic of physics and i want to make it on bernoulli's theorem i wnt it's equation, proof, alternative proof, and some pages on it

2007-01-21 23:54:09 · 8 answers · asked by Anonymous in Physics

what stucture for example wonders of the world
i can shap with the help of the clay with maths related symbols?

2007-01-21 23:53:40 · 2 answers · asked by yasmin m 1 in Mathematics

1)Benzene and ethylbenzene
2) 1-butyne and 2-butyne
3) 2-methylpentane and 2-methyl-2-pentane
4)toluene and 1-methylcyclohexane

Also, can you show me the equations?

2007-01-21 23:51:29 · 5 answers · asked by athame 3 in Chemistry

2007-01-21 23:47:50 · 5 answers · asked by Anonymous in Engineering

2007-01-21 23:47:12 · 22 answers · asked by Anonymous in Mathematics

When a tap ater is boiled, will its hardness increase or decrease? Is it permanent or just temporary? Can I get your explanations? Sources please...

2007-01-21 23:45:32 · 9 answers · asked by Anonymous in Chemistry

detailed discussion of the topic "atomic structure", with some pictures attached on it.

2007-01-21 23:44:28 · 3 answers · asked by mitch 1 in Chemistry

i do not understand why do some people answer me by another question. My question was what happen when all planets align? i dont want the planet to have all the catastropic ending. Please share some knowledge not opinion. thanks.

2007-01-21 23:44:22 · 6 answers · asked by Nula 1 in Astronomy & Space

all australians, if you look out you window to the south you can see a comet pointing to the horizon. how long will it be there? is there a website on it???

2007-01-21 23:43:49 · 3 answers · asked by Anonymous in Astronomy & Space

2007-01-21 23:41:32 · 4 answers · asked by leann_hp28 2 in Chemistry

I am trying to find information on the above, to explain to my son who's 6. My blood type is A Rhesus Negative and due to this i was given the anti-D injection after his birth. I understand the reasons for this but I'm still unsure of the whole Rhesus positive/negative explanation and whether or not my blood type is rare or common?
As you can imagine, explaining this to my son is actually confusing the poor lad more! I need the basic facts so i don't completley misinform him!

2007-01-21 23:40:53 · 16 answers · asked by katie 3 in Biology

can you give me the equations of
(a) blue vitriol exposed to the atmosphere
(b) anhydrous calcium chloride exposed to the atmosphere
(c) Glauber's salt exposed to the atmosphere

these three are hydratse, what can you say about the behavior of these when exposed to the air?

Help me..

2007-01-21 23:38:30 · 5 answers · asked by Anonymous in Chemistry

2007-01-21 23:38:02 · 5 answers · asked by altis 1 in Engineering

1. A patrol car is parked 50 feet from a long warehouse. The revolving light on to ofhte car turns at a rate of 30 revolutions per minute. how fast is the light beam moving along the wall when the beam makes an angle of 30 degrees and an angle of 60 degrees with the line perpendicular from the light to the wall?

2007-01-21 23:37:52 · 3 answers · asked by ashish b 1 in Mathematics

Our bone structure is optimized for Earth's gravity. The bigger the planet, the bigger the gravity. If any living creature ( alien for example ) would to be living in a similar planet like earth, but twice its size, is it possible to have giant spiders, monkeys, fish ?
Comment your awswer/opinion.

2007-01-21 23:37:17 · 7 answers · asked by The Filosophers 2 in Astronomy & Space

larger, smaller, comes forward or gets obscure

2007-01-21 23:35:36 · 8 answers · asked by Arif 1 in Physics

just curious

2007-01-21 23:34:31 · 7 answers · asked by deadman12319 1 in Earth Sciences & Geology

I am interested in small scale hydrogen and oxygen production systems.

2007-01-21 23:28:58 · 4 answers · asked by Robert J 1 in Chemistry

i always get marks that i don't expect from myself in chemistry , i study all reactions dedfinations all my lessons, writing it .i understand my lessons also but there's something wrong .please help?

2007-01-21 23:25:19 · 5 answers · asked by dew m 2 in Chemistry

how does chemistry becomes essential to our eternal struggle for survival, freedom from toil, and for comfort? how essential chemistry is in all of the human needs: food, energy, materials, health, products, that raise the quality of life, and economic vitality?

2007-01-21 23:23:30 · 2 answers · asked by mitch 1 in Chemistry

2007-01-21 23:22:56 · 13 answers · asked by sanika 1 in Mathematics

Is science useful or harmful to us?

2007-01-21 23:20:24 · 14 answers · asked by Anil D 1 in Other - Science

2007-01-21 23:19:12 · 8 answers · asked by alex b 1 in Mathematics

2007-01-21 23:18:18 · 6 answers · asked by BigGee 2 in Weather

Apart from the unsolved mystery of the universe's origin what do you think might be the origin of universe's rules? I am talking about physics/mathematics/chemistry/etc. rules, the ones that scientists study and discover through their study of material reality. Please try to give serious answers. Thanks for that.

2007-01-21 23:17:40 · 5 answers · asked by Alexander K 3 in Astronomy & Space

I have this homework, and I need at least one device used in the 1800's to the 1900's. Help?

2007-01-21 23:15:18 · 4 answers · asked by Denunci 2 in Mathematics

10% of 25% of a number is 20.What is the number?

2007-01-21 23:10:01 · 17 answers · asked by andrew_at241 2 in Mathematics

What is the difference between calibration diagram and calibration curve? Please give me one example.

2007-01-21 23:05:44 · 2 answers · asked by Enko 2 in Engineering