>From Mauro: ...
> It is interesting to continue reading the explanation, > for the force exerted on points inside the sphere. Indeed, I bet it does get interesting! In my own computer simulations, this is where I've had to play god, so-to-speak, and change the algorithm used when the orbiting body presumably passes underneath the "planetary" surface of the main attractor body. At that point one has to jigger a different set of rules since, technically speaking, a point source no longer exists. It's like diving into a swimming pool. The water (the source of gravity) is all around you. I would also imagine the point source formula works best for perfect spherical bodies, and also where the volume of "mass" is assumed to be made of the same material and evenly distributed throughout. Obviously, in nature such uniformity never happens. Take the Earth for example. We have a nickel-iron core. The aggregate "mass" of the core of our planet is decidedly heaver than the collection of elements that make up the surrounding crust. This would imply that if one had a magic elevator shaft that could take a collection of geologists safely all the way to the center of the earth in order to measure one's weight what would systematically be recorded would not necessarily change in ways one might initially predict. For one thing I suspect one's weight would NOT necessarily become gradually less as one travelled through the Earth's crust. It is even conceivable to me that the geologist's weight might even increase slightly as they approached the boundary "surface" of where Earth's nickel-iron core begins. A significant portion of the planet's aggregate planetary mass is located there. Therefore, as the geologist approached this surface boundary the inverse square of the distance (1/R^2) formula might still, more or less, be in effect. I suspect only after our magic elevator has penetrated the surface of the nickel-iron core will our geologists begin to notice that their weight begins to gradually approach zero. Only when the elevator reaches the center of the planet will they feel weightless due to the fact that the collective "mass" of the entire planet is evenly distributed all around them. Regards, Steven Vincent Johnson www.Orionworks.com www.zazzle.com/orionworks
