Editing Collision (section)

===Hypervelocity impacts===
[[File:HRIV Impact.gif|thumb|Video of the hypervelocity impact of NASA’s [[Deep Impact (spacecraft)|Deep Impact probe]] on comet [[Tempel 1]].]]
Hypervelocity is very high [[velocity]], approximately over 3,000 [[metre per second|meters per second]] (11,000&nbsp;km/h, 6,700&nbsp;mph, 10,000&nbsp;ft/s, or [[Mach number|Mach]] 8.8). In particular, hypervelocity is velocity so high that the strength of materials upon impact is very small compared to [[inertia]]l stresses.<ref Name="AIAA">{{cite book
|title= Critical technologies for national defense
|author= Air Force Institute of Technology
|year= 1991
|publisher= AIAA
|location= 
|isbn= 1-56347-009-8
|page= 287
|url= https://books.google.com/books?id=HsEorBWNGWwC&dq=Hypervelocity+3%2C000&pg=PA287}}</ref> Thus, [[metal]]s and [[fluid]]s behave alike under hypervelocity impact. An impact under extreme hypervelocity results in [[vaporize|vaporization]] of the [[impact force|impactor]] and target. For structural metals, hypervelocity is generally considered to be over 2,500&nbsp;m/s (5,600&nbsp;mph, 9,000&nbsp;km/h, 8,200&nbsp;ft/s, or Mach 7.3).  [[Meteorite]] [[impact crater|craters]] are also examples of hypervelocity impacts.