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 Be the first pioneers to continue the Astronomy Discussions at our new Astronomy meeting place...The Space and Astronomy Agora Re: Gravity Research? Forum List | Follow Ups | Post Message | Back to Thread Topics | In Response ToPosted by David W. Anderson on November 7, 1999 01:36:02 UTC

: The outer mass doesn't attract out. As we said earlier the net force on you in the hole at the center of the earth was zero.

Zephram, this doesn't make sense to me. If, as you said, the net force at the center is zero, it must be because the surrounding mass is pulling outward. Also, I didn't say the force "at" the surface is equal to the force at the center. My contention is, that if you isolate a portion of the mass in question (earth in this example) that portion contains within it a center of gravity seperate from the earth's center of gravity. That center would be nearer the surface if, as in my earlier example, the portion in question were conical in shape. My example being, the cone represented by the arctic circle terminating at the center of the earth. If it were posible to lift this cone out of the earth, gravity would begin to fill in the hole. At the same time the cone would be forced by gravity to reshape itself into another sphere. I believe you can take a body of any size and divide it into two portions much like a ball within a larger ball. At some point between the center of the inner, and the surface of the outer ball, is a point where the gravitational attraction is equal because the amount of mass above and below that point is equal. If that is true then it seems to me that this would prohibit a crushing of surface objects by gravitational force. I still believe gravity alone can never crush an object without first trapping it under some other object. Consider the delicate snowflake resting on its edge at the surface of the earth. By the way, I am truely enjoying this exchange and wish I had the skills to do the related math.