On Sun, 17 Aug 2008 17:55:11 -0400, Joseph Gwinn
wrote:

In article ,
Wes wrote:

Bruce in Bangkok wrote:

Gravity? You mean that the closer to the center of the earth we get
the higher the gravitational force? Amazing!

No, it's odder than that. The force of gravity is maximum at the
surface, and drops to zero in two places, being the center of the earth,
and at infinity, beyond the stars. The pressure is maximum at the
center.

Which is a consequence of an even weirder fact - a mass inside a
uniform sphere of finite thickness will experience no net attractive
force from the sphere. Gravity decreases linearly as you penetrate
into the earth.


http://www.ux1.eiu.edu/~cfadd/3050/Ch09Gravity/GrvFld.html


I hope that is the case. Mass has the property of gravity if I remember my
highschool physics correctly. Standing on the surface of the earth the
cetripetal force from the
earth spinning, reduces our attraction to our planet.

I've always wondered what the percentage increase in weight, standing on my
spring scale, would be under the day the world stopped senario.

I don't have a number at hand, but it is significant, and is the reason
the earth bulges near the equator.

Joe Gwinn

a = w^2 * R

where;

a = acceleration
w = earth spin rate = 360 deg/24 hr = 2*pi radians/86400 sec = 7.3E-5
rad/sec
R = earth radius ~= 3960 miles = 20.9E6 ft

so:

a = 3.8E-13 * 20.9E6 ~= 8E-6 ft/sec^2 = 0.25 microg