سميح القاسم
المد يــر العـام *****
التوقيع : 
عدد الرسائل : 3201
تعاليق : شخصيا أختلف مع من يدعي أن البشر على عقل واحد وقدرة واحدة ..
أعتقد أن هناك تمايز أوجدته الطبيعة ، وكرسه الفعل البشري اليومي , والا ما معنى أن يكون الواحد منا متفوقا لدرجة الخيال في حين أن الآخر يكافح لينجو ..
هناك تمايز لابد من اقراره أحببنا ذلك أم كرهنا ، وبفضل هذا التمايز وصلنا الى ما وصلنا اليه والا لكنا كباقي الحيونات لازلنا نعتمد الصيد والالتقاط ونحفر كهوف ومغارات للاختباء
تاريخ التسجيل : 05/10/2009
وســــــــــام النشــــــــــــــاط : 10
 | |  How big is a nanometer? | |
How big is a nanometer?
|  |
A nanometer is a unit of measure. Just like inches, feet and miles. By definition a nanometer
is one-billionth of a meter. A meter is about 39 inches long. A billion
is a thousand times bigger than a million, as a number you write it out
as 1,000,000,000. That is a big number and when you divide a meter into
one billion pieces, well that is very small. So small you cannot see
something a nanometer in size unless you use very powerful microscopes
like atomic force microscopes.
A nanometer is used to measure things that are very small. Atoms and molecules, the smallest pieces of everything around us, are measured in nanometers.
For example a water molecule is less
than one nanometer. A typical germ is about 1,000 nanometers. We can
measure even larger things in nanometers, so a hair is about 100,000
nanometers wide. That is a lot of nanometers! Shaquille
O’Neal, a very tall basketball player, is 2,160,000,000 nanometers tall.
Inside of your computer are tiny
switches that are only 100 nanometers wide. About 1,000 of these
switches can fit across the width of a single hair. Modern computers
have about 100,000,000 switches packed inside, stacked one on top of
another. We use nanotechnology to make these tiny switches.
And a lot of important things happen at the nanometer
scale. We can think of the smell of freshly baked cookies and that is
something that happens on the nanometer scale. The molecules that are
released from the cookie when it bakes are less than a nanometer in
size and so they are carried through the air to our noses because they
are so small. Gravity does not have much of an effect on them and so
they float along. They reach our noses and when they are very very
close, less than a nanometer away, we can smell them. |
|
| |
|
اليوم في 1:55 pm من طرف