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Re: (meteorobs) Fwd: How fast do Meteors go?




----- Original Message -----
From: "Lew Gramer" <dedalus@latrade.com>

> according to my understanding, the single
> most important factor in brightness (other than distance from the
observer!)
> is sort of like the mantra for real estate developers: speed, speed,
speed.
>
> Recall that the radiation generated by these tiny, fluffy particles during
> atmospheric entry is generated by friction, and derives ultimately from
the
> kinetic energy of the fluff. And as folks remember from High School
physics,
> the formula for kinetic energy is "1/2 mv^2" ("one half of em vee
squared").
> Naturally, as 'v' increases, the amount of kinetic energy that is
available
> to be released by friction also increases - very rapidly!

For our mathematical freaks:

According to Jachia et al. (1967) the relationship between mass, velocity,
entry-angle and brightness is:

log M(m)=2.98-0.44m-3.89log V[inf]-0.67log(sin h)

in which m=magnitude, M=mass in kg, V[inf] is speed (infinite, not
geocentric) and h is the zenith distance of the radiant.

But please don't ask me why this is this particular relationship. I realy
don't know.

- Marco

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