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Re: Sauropods vs. Gravity
At 03:28 PM 3/3/2002, you wrote:
Although I don't agree with Colin's thoughts
on possible past gravity
fluctuations, I feel obligated to point out that lower gravity in the
past does not imply that the earth was physically smaller then, or that
it is more massive now. For example, a phase change in the core,
mantle, or crust could cause the earth to be smaller in diameter now,
which would result in greater gravity at the surface (I don't believe to
have been the case). For a given mass, a smaller radius in the past
would have resulted in greater surface gravity then. If the earth
were smaller in the past, and less massive, the surface gravity could
have been either less or more, depending upon how much smaller and how
much less mass. Planets smaller than the earth can have greater
surface gravity, even with
less mass than the earth, just as they can have lower surface gravity
with more mass.
I am confused. I thought gravity was based on mass, not
volume. Changing the diameter of the Earth would not change its
mass. How would the gravity change?
I looked up this topic and found this from the USGS:
"Gravitation is the force of attraction between two bodies, such as
the Earth and our body. The strength of this attraction depends on
the mass of the two bodies and the distance between them."
What am I missing?
Darryl Jones <firstname.lastname@example.org>
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