Meteorology
Big news this weekend has been the Russian meteor which caused a fair bit of panic and destruction in the Urals. Quite frightening that a 17meter diameter chunk of rock could suddenly pass into our atmosphere. I was particularly interested by the statements about it exploding with an energy equivalent to 20 Hiroshima bombs. Why would it explode, rock is not an explosive. To explode means that the rock disintegrates and all the pieces fly apart. In a bomb the energy required comes from chemical or nuclear energy but what happens with the meteor is that it is moving so fast that when it enters the atmosphere the friction between the air and the rock first heats it up, then the force of the air against the rock breaks it up. So the energy for the explosion comes from the kinetic energy of the rock itself not a chemical reaction. Read more here Dot Physics.
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