Here’s a fun interview with the Mythbusters. I don’t get this, though:
My favorite episode, that I think the science is the most right, is ”Bullets Fired Up”: Will a bullet that you fire directly into the air kill you when it comes back down? We tried it in several different ways, and every single way we tried it — from a shop experiment, to a scaled outdoor experiment, to a full-size outdoor experiment where we fired a full clip of 9mm rounds into the air out in the desert — confirmed the same results. If it’s coming straight down, it won’t kill you. But if you fire it on an angle of even two degrees, it stays on a ballistic trajectory and it will kill you. So when you see someone in a movie fire their automatic rifle on kind of a spray up into the sky, probably all of those bullets are actually deadly. The amount of data we collected on it was more than anybody up to that point had ever achieved on firing bullets into the air.
I don’t get what they’re saying here. Why would it come down any harder if it’s at a slight angle? How did they determine whether or not “it would kill you”? If it’s in a vacuum, it should come down with exactly the same vertical velocity component it had when it left the gun (except reversed), but the atmosphere complicates things. It seems to me that any bullet fired in the air is going to be coming down at terminal velocity, unless the potential energy is so high that it doesn’t have time to get to terminal velocity before it hits the ground, but that’s pretty hard to believe. When it leaves the muzzle of the gun, it’s supersonic, but I would think that it won’t be able to be going that fast when it falls back down, because of air drag. This seems like something that should be simulatable with CFD (it might even be possible to do it analytically, if the bullet was round).