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[return to "NASA System Predicts Impact of a Small Asteroid over Germany"]
1. jl6+L5[view] [source] 2024-01-25 07:15:49
>>alex_y+(OP)
> scattered small meteorites on the ground at the impact site about 37 miles (60 kilometers) west of Berlin

Do we know how fast those small meteorites are travelling when they hit the ground? Are they like bullets or more like snowflakes?

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2. somena+3l[view] [source] 2024-01-25 10:16:47
>>jl6+L5
You can very roughly estimate the lower bound pretty easily, by assuming a meteorite to be roughly spherical and ballparking the drag coefficient. So its volume = 4/3 * pi * r^3. Its surface area = 4 * pi * r^2. We can assume half of its surface area is its cross section. So just change the 4 to a 2 above to get the cross sectional area. Meteors generally have a density up to around the 8000 kg/m^3 range. So now we have everything we need to calculate terminal velocity using a calculator. [1]

for a 1m meteorite:

mass = 4/3 * pi * 0.5^3 * 8000 = 4188 kg

area = 2 * pi * 0.5^3 = 0.78 m

The defaults for density and drag coefficient are fine enough. And we get a result of at least 500m/s, assuming air resistance is sufficient to slow it down to terminal velocity. The exact number will vary quite a lot - especially as this is for a whole meter sized meteorite that doesn't disintegrate, but this is at least a reasonable ballpark. So the tl/dr would be: more like a bullet, but with somewhere around 140,000 times the kinetic energy, for a 1m meteorite.

[1] - https://www.gigacalculator.com/calculators/terminal-velocity...

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