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Date: 1991 


Question:
I HAVE A QUESTION ABOUT A FALLING OBJECT. IF YOU DROPPED A OBJECT FOR 100,00 FEET ABOVE SEA LEVEL WOULD IT BURN UP BEACAUSE OF AIR FRICTION OR WOULD IT FREEZE FROM THE COLDNESS AND THIN AIR? THANKS.



Replies:
What happens when an object is dropped in air? It speeds up for a while (because of gravity) and then comes to a final "terminal" velocity (which depends on the density of the air, and so it would actually slow down a little as it got closer to the ground). If this terminal velocity was really fast it might not quite reach it before hitting the ground, of course. Anyway, the friction of the air always causes heating of the object, except in one case - when the object contains water (or something else that evaporates easily). Then the air rushing past acts like the wind when they talk about "wind chill factors" - it cools it down (because the evaporating water takes some of the objects heat with it). But when the water's all been taken out, the object will start to heat up again... (and may start to before that - I think it is a little complicated).

Arthur Smith



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