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Obsidian hydration dating (OHD) is a geochemical method of determining age in either absolute or relative terms of an artifact made of obsidian.. Obsidian is a volcanic glass that was used by prehistoric people as a raw material in the manufacture of stone tools such as projectile points, knives, or other cutting tools through knapping, or breaking off pieces in a controlled manner, such as ...
Obsidian (/ ə b ˈ s ɪ d i. ən, ɒ b-/ əb-SID-ee-ən ob-) [5] is a naturally occurring volcanic glass formed when lava extruded from a volcano cools rapidly with minimal crystal growth.
Volcanic glass is the amorphous (uncrystallized) product of rapidly cooling magma. Like all types of glass , it is a state of matter intermediate between the closely packed, highly ordered array of a crystal and the highly disordered array of liquid . [ 1 ]
Thermal conduction rate, thermal current, thermal/heat flux, thermal power transfer P = / W ML 2 T −3: Thermal intensity I = / W⋅m −2: MT −3: Thermal/heat flux density (vector analogue of thermal intensity above) q
Obsidian is usually of rhyolitic composition, and it has been used for tools since prehistoric times. [34] Obsidian scalpels have been investigated for use in delicate surgery. [ 35 ] Pumice, also typically of rhyolitic composition, finds important uses as an abrasive , in concrete , [ 36 ] and as a soil amendment . [ 37 ]
Convection cooling is sometimes said to be governed by "Newton's law of cooling." When the heat transfer coefficient is independent, or relatively independent, of the temperature difference between object and environment, Newton's law is followed. The law holds well for forced air and pumped liquid cooling, where the fluid velocity does not ...
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The heat transfer rate can be written using Newton's law of cooling as = (), where h is the heat transfer coefficient and A is the heat transfer surface area. Because heat transfer at the surface is by conduction, the same quantity can be expressed in terms of the thermal conductivity k: