You realize that your question has been answered by post #5 right?I'm afraid I don't see the answer [in wikipedia]. I'll try to answer it then.
Or did you have a different question I missed?
"acceleraton" is fine. "acceleration of gravity" is better. "free-fall acceleration of gravity" is best.Gravity acceleration. I should have said "force" I guess.
You could also have talked about gravitatonal potential (not to be confused with potential energy).
The force of gravity, by comparison, varies with mass as well as separation, so it is not as useful for your purposes: you be constantly have to qualify every statement.
Only for a uniform hollow spherical shell. Only inside the hollow part.So since every molecule is static, that means acceleration vectors cancel at every point inside a planet, not just the center?
The calculation will have some cancellations in it inside, pretty much, any mass distribution though.
To appreciate it you really need calculus - you divide the mass up into lots of small sub-masses and work out the gravity, on a test mass, at the point of interest, due to each sub-mass by itself. Then add them all up (remembering that the force of gravity is a vector) and divide by the test mass. This gets you the acceleration due to gravity at that point.
Without calculus you can see the effect by doing the same calculation for different arrangements of discrete masses.