.... in order that it just barely escapes the planet's gravity is called the "escape velocity." As you would expect, the escape velocity depends on the mass of the planet: if the planet is extremely massive, then its gravity is very strong, and the escape velocity is high. A lighter planet would have a smaller escape velocity. The escape velocity also depends on how far you are from the planet's center: the closer you are, the higher the escape velocity . The Earth's escape velocity is 11.2 kilometers per second (about 25,000 M.P.H.), while the Moon's is only 2.4 ki .....

.... Surgery Devices Branch Division of General Restorative Devices and the Office Of Device Evaluation all require (ODE documents 6). The Chemical Characterization, is an important test. It does all of the following. If fabrication of the device involves curing of polymeric components by chemical crosslinking, then data establishing should be provided. This may be done by a various methods, for example: Measurement of Young’s modulus at low strain, as this is approximately proportional to crosslink density. Measurement of equilibrium swelling of the polyme .....

.... problem of gas exchange, as water is not present in all of the terrestrial environment. Terrestrial vertebrates have developed lungs to solve this problem. Air enters through the nasal passages, or the mouth, passes through the trachea, then branches off at the two bronchi, and goes through many branching passages called bronchioles, which end in alveoli. Alveoli are sack-like structures where the circulatory system meets the respiratory system. Since terrestrial vertebrates do not live in water, they need to develop a means of conserving water. One way we do .....

.... longer be harmful. A very advantageous way of storing radioactive wastes is by a process called 'vitrification'. Vitrification is a semi-continuous process that enables the following operations to be carried out with the same equipment: evaporation of the waste solution mixed with the additives necesary for the production of borosilicate glass, calcination and elaboration of the glass. These operations are carried out in a metallic pot that is heated in an induction furnace. The vitrification of one load of wastes comprises of the following stages. The f .....

.... introduce smoke and other, less visible, by-products into the atmosphere. Although wind and rain occasionally wash away the smoke given off by power plants and cars, the cumulative effect of air pollution poses a grave threat to humans and the environment. In many places smoke from factories and cars combines with naturally occurring fog to form smog. Smog has been long recognized as a potential cause of death, especially for elderly persons and those with severe respiratory ailments (like asthma). Air pollution originally resulted from large-scale use of heatin .....

.... have been exposed to the chemicals mentioned above. In laboratory studies, high doses are required to give weak hormone activity. These doses are not likely to be encountered in the environment. However the process of bioaccumulation can result in top-level predators such as humans to have contaminants at levels many million times greater than the environmental background levels (Guilette 1994). In field studies, toxicity caused by endocrine disruption has been associated with the presence of certain pollutants. Findings from such studies include: reproductive .....

.... with water, oxygen, and oxidants. This forms a mild solution of sulfuric acid and nitric acid. These chemical reactions that change air pollution into acid rain can take from several hours to several days. Sunlight increases the rate of these reactions. Rainwater, snow, fog, and other forms of precipitation containing these mild solutions of sulfuric and nitric acids fall to the ground as acid rain. Years ago, when smokestacks were only a few stories tall, pollution from the smokestacks usually stayed near the ground and settled on the land nearby. Thi .....

.... of sulfur dioxide and 20.5 million tons of nitrogen oxides to our atmosphere worldwide. When fossil fuels are ignited like oil and coal, they release carbon dioxide, a so-called greenhouse gas that traps heat within the earth's atmosphere which causes global warming that is taking place right now. Also, it releases sulfur dioxide, nitrogen oxide and various metals (mercury, aluminum) that are released into the atmosphere that reacts with other airborne chemicals (water vapor and sunlight) to produce sulfuric and nitric acid which later can be carried long .....