I was reading and saw this post
So, my question is: Assuming the hypothetical planet was identical to earth is size and gravity but a total vacuum and completely "flat" in such there are no hills, mountains, etc... obstacles in the way, how fast would a bullet have to travel to essentially beat gravity and continue to stay at the same height and travel around the world to essentially hit the firearm in which it was shot out of? And roughly, how long would it take for said projectile to go around the "earth" and hit the firearm?
If it's not clear by what I'm saying, I don't mean beat gravity as in fly out to outer space like a rocket, or if there was zero gravity it would just fly off because nothing is keeping it here. I assume there has to be a certain speed at which you can fire a firearm from about 5 feet in the air to which gravity affects the bullet at the same rate that the curvature of the "earth" happens. Gravity would pull it down at the same rate as the bullet would "rise" above the ground making it stay at 5 feet constantly around the planet.