let's say you are sitting in a chair and live on a nice tropical island in the equator. Right then and there you are gonig roughly 1,000 miles per hour due to the earth's spin. everything arround you is also going that fast but to you it's all standing still. a car passing heading east is going that + it's speed. going west - it's speed.
now let's take it a bit further.
the earth rotates arround the sun at 66,500 mph. add anohter 1,000 from rotation at points where your placement upon the earth lines up with the earth orbit arround the sun and obiously - that when opposite side during it's orbit.
OMG EVERYONE IS BREAKING THE SPEED LIMIT !!!
wait that's not all!!!
If the big bang theory is true however fast the mass was ejected is how fast the stars/solar systems ect is traveling away from 1 fixed point. We may allready be going at the speed of light (or close to it).
if object a is traveling at the speed of light east and object b is traveling in the oposite direction at the speed of light. If object A can be preceived to be standing still object b will be going 2x the speed of light from the point of preception of object a.
We consider objects when they impact each other to head on we considere both speeds combined to give us an impact speed. so techincally yes you could have an impact of 2x the speed of light if 2 objects going the speed of light hit each other head on.
The magnitude of the velocity of the speed of light is the same no matter what frame of reference you are in.
Gravity is attraction between two bodies with mass. Gravity weakens with distance according to inverse square law. Speed needed to escape gravitational pull of an object is referred to as "escape velocity".
Event horizon of a black hole is a boundary where escape velocity is greater than the speed of light (nothing in our universe can go faster than speed of light, so it's commonly referred to as point of no escape, once inside event horizon of a black hole, you cannot get out because every path will lead to center of black hole). Schwarzschild radius: imagine that all mass of an object is located inside a sphere, and escape velocity from the surface of a sphere is equal to speed of light. Schwarzschild radius would be distance from the center of a sphere (radius of Sun is around 3 km, Earth's around a centimeter, in layman's terms, event horizon of a black hole with mass equal to Earth would be a two centimeters wide). Light orbiting black hole is called photon sphere.