Comment by bibelo
4 days ago
Thank you for that precision "without continued propulsion", because when talking about rockets, physics teachers always talk about escape velocity, as if it was an absolutely necessary condition to escape earth's gravity.
But can't you escape gravity slower, just by going higher and higher at lower speed? Like a plane? (ie not vertically, but at an angle)
If you don't accelerate, my understanding is that you will slow down. In other words, it takes more and more energy to escape orbit. Eventually, if you don't accelerate, your speed drops to zero and you "fall back down". Escape velocity is about how much energy you put into your motion, not the velocity as such.
No, the absolute minimum speed IS required. Anything below that and you’re just making your orbit elliptical.
That seems wrong. If you have a way to maintain enough propulsion for long enough you can escape the gravity well at any arbitrarily low speed. You "just" need to maintain that speed long enough for the escape velocity from the gravity well to go below it as it diminishes with distance from the mass.
Oh yeah, 1.01 Gs of endless propulsion will work. I was just arguing in the context of existing technology.