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Дата индексирования: Tue Oct 2 19:06:33 2012
Кодировка:
Поисковые слова: asteroid
Worked Example 02

Worked Example 02

The Question

A spherical meteorite of radius 3m enters the Earth's atmosphere at an altitude of 100km and a speed (relative to the Earth) of 30 km/s. The atmosphere slows it down, so when it hits the Earth's surface it is travelling at only 1 km/s. If half of the heat generated as it passes through the atmosphere is absorbed by the meteorite, how hot will it be when it is about to land? You may assume that the meteorite is a good conductor, so the heat is spread evenly throughout, that it is made of Iron, with a specific heat capacity of 450 J Kg-1 K-1, and that it started off at a temperature of 270K.

The Answer

(Note - the the equation I derive for Delta T near the end (in black, top right-hand corner), I mistakenly left the masses in the kinetic energy terms. However, the number I calculated (500,000 K) is correct, as is the discussion that follows it.

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