Re:Virgin Galactic successfully reaches space
by sonnyblarney on Thursday December 13, 2018 @09:25PM
(#18677944)
The force of gravity is always orthogonal to the direction of motion when in orbit. So never loses momentum. Which is why the moon is still going around the earth a billion years later and has not 'fallen' into it.
Re:Virgin Galactic successfully reaches space
by Armisael16 on Friday December 14, 2018 @10:51AM
(#18681631)
This is only true for circular orbits. Itβs pretty transparently obvious that elliptical orbits move closer to and farther from the center of mass (and lose and gain momentum accordingly).
Re:Virgin Galactic successfully reaches space
by ethbro on Thursday December 13, 2018 @09:59PM
(#18678094)
We're talking suborbital velocities here.
If I'm wrong, I'd love to hear exactly why, but regurgitating basic physics doesn't resolve the difficulties in modelling a straight flight path around a curved surface, in relation to a dropped object.
Does this hold true as an object's ballistic trajectory approaches significant fractions of a planet's diameter?
Granted, the object is constantly being accelerated towards the center of the planet.
But that force vector's direction changes with respect to the initial "horizontal" launch vector as the object continues on a straight path, until they're longer orthogonal.