Explanations of basic orbital mechanics that I can find all go,
$$\frac{v_{satellite}^2}{r} = a_c = \frac{F_{gravity}}{M_{planet}} = \frac{(\frac{G M_a M_s}{r^2})}{M_{planet}}$$
, and so you get a velocity,
$$v_{satellite}=\sqrt{\frac{GM_{planet}}{r}}$$
. So you need that velocity to orbit earth at that radius. But it doesn't answer alot of questions like:
How much can you increase or decrease your velocity for this v and r relationship to stop?
What changes when you reach those points which makes you fly away or crash into the earth?
Why would increasing v of the satellite effect something perpendicular like the ac?
Why does having a centripetal acceleration equal the force from gravity, 9.81, prevent you from crashing?
