• arctanthrope@lemmy.world
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    7 days ago

    I’ll be the other guy: even if they could fly, the escape velocity of the moon is still 2380m/s, more than 25× faster than the fastest bird flight

    • overcast5348@lemmy.world
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      7 days ago

      Probably a dumb question, but here it goes-

      Escape velocity is the velocity needed to escape the moon/planet’s gravity without any further propulsion, right?

      A stone thrown upwards would slowly lose its velocity and then start falling back because there’s no engine to keep it going.

      But an “ideal spherical bird” could keep going at a constant velocity of 20m/s to escape whatever planet it wants to leave, right?

      Does the escape velocity really matter here? (Assuming that all other issues like lack of air are ignored)

      • arctanthrope@lemmy.world
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        7 days ago

        technically yes, the issue is eventually you run out of atmosphere to push off of to maintain that speed, and if you don’t have enough momentum at that point to take you the rest of the way, then you’ll fall back down. but I suppose if we’re already assuming that they can fly without atmosphere, then that doesn’t matter