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The shockwave from the Chelyabinsk meteor that rocketed across the Russian morning sky on 15 February 2013. In physics, a shock wave (also spelled shockwave), or shock, is a type of propagating disturbance that moves faster than the local speed of sound in the medium. Like an ordinary wave, a shock wave carries energy and can propagate through ...
In demography, demographic transition is a phenomenon and theory which refers to the historical shift from high birth rates and high death rates to low birth rates and low death rates, as societies attain more technology, education (especially of women) and economic development. [1] The demographic transition has occurred in most of the world ...
Population change is simply the change in the number of people in a specified area during a specific time period.Demographics (or demography) is the study of population statistics, their variation and its causes.
The Demography of the World Population from 1950 to 2100. Data source: United Nations — World Population Prospects 2017. Demography (from Ancient Greek δῆμος (dêmos) 'people, society' and -γραφία (-graphía) 'writing, drawing, description') [1] is the statistical study of human populations: their size, composition (e.g., ethnic group, age), and how they change through the ...
An earthquake warning system or earthquake alarm system is a system of accelerometers, seismometers, communication, computers, and alarms that is devised for rapidly notifying adjoining regions of a substantial earthquake once one begins. This is not the same as earthquake prediction, which is currently not capable of producing decisive event ...
Emergency medicine, trauma surgery. A blast injury is a complex type of physical trauma resulting from direct or indirect exposure to an explosion. [1] Blast injuries occur with the detonation of high-order explosives as well as the deflagration of low order explosives. These injuries are compounded when the explosion occurs in a confined space.
Population growth is the increase in the number of people in a population or dispersed group. Actual global human population growth amounts to around 83 million annually, or 1.1% per year. [ 2 ] The global population has grown from 1 billion in 1800 to 8.1 billion in 2024. [ 3 ] The UN projected population to keep growing, and estimates have ...
Conical shockwave with its hyperbola-shaped ground contact zone in yellow. A sonic boom is a sound associated with shock waves created when an object travels through the air faster than the speed of sound. Sonic booms generate enormous amounts of sound energy, sounding similar to an explosion or a thunderclap to the human ear.