... engines, and rockets on the ground under pre-set conditions. With a wind tunnel you can chose the air speed, pressure, altitude and temperature to name a few things. A wind tunnel is usually has a tube like appearance with which wind is produced by a large fan to flow over what they are testing (plane, missiles, rockets, etc.)or a model of it. The object in the wind tunnel is fixed and placed in the test section of the tunnel and instruments are placed on the model to record the aerodynamic forces acting on the model. Types of Wind Tunnels There are four basic types of wind tunnels. Which are low subsonic, ...

... central nervous system. Mercury's Effect on the Environment and People Mercury is one of the biggest environmental problems that exist because it is hard to get of once in the environment. In the past, mercury was used to make things like paper, put in paint and thermometers, and as an agricultural pesticide. The Minamata Disease is a good example of what could happen if mercury enters into the environment. In the mid 1950's, more than 100 Japanese were poisoned by fish that contained methyl mercury. The mercury came from industrial waste that had been dumped into the bay where the fish were caught. The mercu ...

... This offers the possibility of creating entirely new genes with commercially or medically desirable properties. While the potential benefits of genetic engineering are considerable, so may be the potential dangers. For example, the introduction of cancer-causing genes into a common infectious organism, such as the influenza virus, could be hazardous. We have come to believe that all human beings are equal; but even more firmly, we are taught to believe each one of us is unique. Is that idea undercut by cloning? That is, if you can deliberately make any number of copies of an indivi ...

... the hot fusion community, and many in the news media have ignored the continuing cold fusion research. But cold fusion is far from dead. It is alive not only in dozens of laboratories in the United States, but in numerous foreign research centers, particularly in Japan. Cold fusion is a real but still incompletely explained energy-producing phenomenon that occurs when ordinary hydrogen and the special form of hydrogen called deuterium are brought together with metals, such as palladium, titanium, and nickel. Usually, some triggering mechanism, such as electricity or even acoustic energy, is required to provoke the " ...

... stars. Shortly after Archimedes, Ctesibus created the Clepsydra in the 2nd century BC. A more elaborate version of the common water clock, the Clepsydra was quite popular in ancient Greece. However, the development of stereography by Hipparchos in 150 BC. radically altered physical representations of the heavens. By integrating stereography with the Clepsydra and the celestial sphere, humanity was capable of creating more practical and accurate devices for measuring time—the anaphoric clock and the astrolabe. Although Ptolemy was familiar with both the anaphoric clock and the astrolabe, I believe that the develop ...

... was the start of time and space. The matter and radiation of that early stage rapidly expanded and cooled. Several million years later, it condensed into galaxies. The universe has continued to expand, and the galaxies have continued moving away from each other ever since. Today the universe is still expanding, as astronomers have observed. The Steady State model says that the universe does not evolve or change in time. There was no beginning in the past, nor will there be change in the future. This model assumes the perfect cosmological principle. This principle says that the universe is the same everywh ...

... to do just about everything. Performance enhancing drugs and supplements are just the thing for someone who is looking toward “bulking up” and increasing strength in a small amount of time. Steroids allow its users to recover more quickly from exercise than a natural athlete, so they can return to the gym sooner for another workout. So that means less work equals more muscle gain, compared to working out normally with no supplement. Who wouldn’t want that? Think about all the pain you wouldn’t have to go through doing all those reps. With a performance enhancing drug, you could d ...

... the sea otters and the kelp-forests was provided because of a accident of history, the over-exploitation of sea otters in the Pacific maritime fur trade. The study compared areas where sea otters were abundant with nearby areas to area's where they're almost extinct. By doing this comparison of the sea otters coastal system it was possible to gain much insight into the sea otter ecological role in kelp-forest ecosystem. Over the years it's been possible for us to observe the kelp-forest ecosystem over-time, thanks to the massive growth of the sea otters population we observed the change from otter- ...

... a central nucleus, composed of protons and neutrons. each electron carries one negative charge and each proton one positive charge. Neutrons carry no charge. Every atom has the same number of electrons as there are protons, so, on the whole, it is electrically neutral. The electrons have discrete kinetic energy levels, which increase with the orbital radius. When atoms bond together to form a solid, the electron energy levels merge into bands. In electrical conductors, these bands are continuous but in insulators and semiconductors there is an "energy gap", in which no electron orbits can exist, between the inner ...

... the months of summer. The vernal equinox occurs when the sun is directly over the equator and it complies with the first day of spring. It also means that the sun is an equal distance from the north and south poles. At this time both hemispheres have the same amount of sun as the sun makes its way north. Before the vernal equinox the sun hits the northern surface at an angle instead of hitting it directly. By hitting the earth's surface at an angle there is not as much radiation warming the surface. As the earth rotates and the sun moves further north the temperature increases and the weather turns warmer ...