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Shock wave. The sound barrier or sonic barrier is the large increase in aerodynamic drag and other undesirable effects experienced by an aircraft or other object when it approaches the speed of sound. When aircraft first approached the speed of sound, these effects were seen as constituting a barrier, making faster speeds very difficult or ...
The field strength of electromagnetic radiation is measured in volts per meter (V/m). [ 2]: 139. The most common health hazard of radiation is sunburn, which causes between approximately 100,000 and 1 million new skin cancers annually in the United States. [ 3][ 4] In 2011, the World Health Organization (WHO) and the International Agency for ...
Underwater vision. Scuba diver with bifocal lenses fitted to a mask. Underwater vision is the ability to see objects underwater, and this is significantly affected by several factors. Underwater, objects are less visible because of lower levels of natural illumination caused by rapid attenuation of light with distance passed through the water.
Elevated workplace or environmental noise can cause hearing impairment, tinnitus, hypertension, ischemic heart disease, annoyance, and sleep disturbance. [ 3][ 4] Changes in the immune system and birth defects have been also attributed to noise exposure. [ 5] Although age-related health effects ( presbycusis) occur naturally with age, [ 6] in ...
Radioactive contamination, also called radiological pollution, is the deposition of, or presence of radioactive substances on surfaces or within solids, liquids, or gases (including the human body), where their presence is unintended or undesirable (from the International Atomic Energy Agency (IAEA) definition). [ 3]
A noise barrier (also called a soundwall, noise wall, sound berm, sound barrier, or acoustical barrier) is an exterior structure designed to protect inhabitants of sensitive land use areas from noise pollution. Noise barriers are the most effective method of mitigating roadway, railway, and industrial noise sources – other than cessation of ...
The speed of sound is the distance travelled per unit of time by a sound wave as it propagates through an elastic medium. More simply, the speed of sound is how fast vibrations travel. At 20 °C (68 °F), the speed of sound in air is about 343 m/s (1,125 ft/s; 1,235 km/h; 767 mph; 667 kn ), or 1 km in 2.91 s or one mile in 4.69 s.
t. e. Visual pollution refers to the visible deterioration and negative aesthetic quality of the natural and human-made landscapes around people and to the study of secondary impacts of manmade interventions. [ 1] It also refers to the impacts pollution has in impairing the quality of the landscape, formed from compounding sources of pollution ...