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Theory of the Fireball

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which is a pure number, and small: The calculation could be improved by<br />

not neglecting 5 compared with H .<br />

a<br />

According to (6.11) t'ne fireball is used up at <strong>the</strong> time x defined<br />

X<br />

(6.16)<br />

This relation is valid (granted <strong>the</strong> approximations we have made) what-<br />

ever <strong>the</strong> relation between pressure and time, f (x) * This generality is<br />

useful for sea level explosions, where p is only 5 times ambient pressure:<br />

a<br />

The relation between p and t cm <strong>the</strong>n be taken from a machine calculation<br />

( or observation) .<br />

For higher altitude, let us say h > LO b, pa = 5( p /p )1/3 is<br />

1 0<br />

sufficiently above, <strong>the</strong> ambient pressure, pl/po, so that <strong>the</strong> shock is<br />

still strong and we may use<br />

f(x) = x 1.2<br />

Tnen (6.11) becomes<br />

75<br />

r

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