Simple Machines
.... the W=F*d equation the trade of between force and distance is as you
use a machine the force goes down and distance goes up. If there was no friction
they would be equal and trade.
There are six simple machines. They are a lever, pulleys, inclined plain,
wheel and axle, screw, and wedge. The lever is used very often an example of a
lever is a broom. Your hand is the fulcrum and when you sweep it is a lever. A
lever consist of a fulcrum, effort, and resistance. A pulley is used to lift or
pull objects with a advantage. To get a advantage it matters how many lines are
going to the load. For example if there is 3 lines to the .....
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Solar Cells
.... there is an
"energy gap", in which no electron orbits can exist, between the inner valence
band and outer conduction band [Book 1]. Valence electrons help to bind together
the atoms in a solid by orbiting 2 adjacent nucleii, while conduction electrons,
being less closely bound to the nucleii, are free to move in response to an
applied voltage or electric field. The fewer conduction electrons there are, the
higher the electrical resistivity of the material.
In semiconductors, the materials from which solar sells are made, the
energy gap Eg is fairly small. Because of this, electrons in the valence band
can easily .....
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Mechanics: Statics And Dynamics
.... of Archimedes covering bouyancy and the
lever were recorded before 200 B.C. Our modern knowledge of gravity and motion
was established by Isaac Newton (1642-1727).
Mechanics can be divided into two parts: (1) Statics, which relate to
bodies at rest, and (2) dynamics, which deal with bodies in motion. In this
paper we will explore the static dimension of mechanics and discuss the various
types of force on an object and the different strength of materials.
The term strength of materials refers to the ability of the individual
parts of a machine or structure to resist loads. It also permits the selection
of materials and .....
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Stratospheric Observatory For Infrared Astronomy
.... flight operations by the year 2001.
.....
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Superconductivity
.... and between different materials but to do that,
they require the right amount of energy and an "empty" slot in the band they
enter. The metallic conductors have a lot of these slots and this is where the
free electrons will head when voltage (energy) is applied. A simpler way to look
at this is to think of atoms aligned in a straight line (wire). if we add an
electron to the first atom of the line, that atom would have an excess of
electrons so it releases an other electron which will go to the second atom and
the process repeats again and again until an electron pops out from the end of
the wire. We can then say that conduction .....
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Surface Tension
.... of tension on the thin film of soap, is another
example of this force; surface tension alone can support a needle placed
horizontally on a water surface.
Surface tension depends mainly upon the forces attraction between the
particles within the given liquid and also upon the gas, solid, or liquid in
contact with it. The molecules in a drop of water, for example, attract each
other weakly. Water molecules well inside the drop may be thought of as being
attracted equally in all directions by the surrounding molecules. However if
surface molecules could be displaced slightly outward from the surface, they
would be attrac .....
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The Big Bang And The Steady State Model
.... perfect cosmological principle. This principle
says that the universe is the same everywhere on the large scale, at all times.2
It maintains the same average density of matter forever.
There are observational evidences found that can prove the Big Bang model
is more reasonable than the Steady State model. First, the redshifts of distant
galaxies. Redshift is a Doppler effect which states that if a galaxy is moving
away, the spectral line of that galaxy observed will have a shift to the red end.
The faster the galaxy moves, the more shift it has. If the galaxy is moving
closer, the spectral line will show a blue shift. If .....
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The Chaos Theory
.... up with the Chaos Theory was
Mitchell Feigenbaum, who was one of a handful of scientists at Los Alamos, New
Mexico when he first started thinking about Chaos. Feigenbaum was a little
known scientist from New York, with only one published work to his name. He
was working on nothing very important, like quasi periodicity, in which he and
only he had 26 hour days instead of the usual 24. He gave that up because he
could not bear to wake up to setting sun, which happened periodically. He
spent most of time watching clouds from the hiking trails above the laboratory.
To him could represented a side of nature that the mainstream .....
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The Nuclear Power Debate
.... next century if fossil fuels continue to be used, even at
present global levels. The Panel claims that for carbon dioxide to be
stabilised to safe levels, a 50-80% reduction in all emissions would be required.
The United Nations has predicted a world population growth from 5.5
billion to 8.5 billion by the year 2025, meaning demand for energy will increase.
Nuclear power is the only practical source, in consideration for the
environment, cost and efficiency. Coal-fired generation of electricity would
increase carbon dioxide emissions, and renewable sources such as solar and hydro,
are not suitable for large scale power genera .....
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Thoeries Of Evolution
.... most famous book, On the Origin of Species by Means of
Natural Selection (1859), is a landmark in human understanding of nature.
Pointing to variability within species, Darwin observed that while offspring
inherit a resemblance to their parents, they are not identical to them. He
further noted that some of the differences between offspring and parents were
not due soley to the environment but were themselves often inheritable. Animal
breeders were often able to change the characteristics of domestic animals by
selecting for reproduction those individuals with the most desirable qualities.
Darwin reasoned that, in nature, individ .....
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The Creation Of The Universe
.... .....
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Frogs
.... The second stage, in which
the hind legs grow, is called “prometamorphosis,” and lasts about 21 days. When
the legs are about as long as the body, the third stage, which is called “
metamorphic climax,” and takes place very rapidly, begins. During this last
stage, which lasts about a week, many great changes occur. They lungs complete
their development, and the gills disappear. The skin gets thicker, nostrils
form, and the tail is completely resorbed.
Most frogs prefer moist regions, and many kinds live in the water.
Because frogs absorb oxygen in water through their skin, they can stay
underwater for long periods of time. A .....
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