Thread: Gravity

Does a larger planet = a stronger gravitational force on that planet? I'm thinking of the moon being smaller than the earth, and also having a weaker gravitational force on its surface, but doesn't gravitational force grow weaker the farther away you get from something? There's that equation used to find gravitational force, and I'm not sure of the whole thing, but I know it has a bunch of stuff over r squared, which means that as the radius increases, the gravitational force decreases... Maybe it has nothing to do with this, I really don't know. (that's why I'm asking ) And by the way, this isn't hw or anything, I'm just curious.

lets say it like this, if we assume that all planets in the inner part of the solersystem have the same density. then the amount of mass increase with the cube of the radius, while the gravitational force decrease with the square. conclution, mass increase faster than gravitation decrease therefore the total change is a increase of gravitational force. this is almost allways true for planets even thoue they dont have the same density

ok, makes sense, thanks

The force of gravity from within a spherical shell is zero. If you think of the Earth as a bunch of increasing size spherical shells, then the the closer you are to the surface, the greater the gravitational pull. As you move away or towards the center of the Earth from the center, then the strength will become weaker.

notice, this is withiin a body

The universe is expanding but why is the earth going further from the sun? Is the mass changing? Or is the force of the expanding universe greater than the attraction of earth and sun?

those have nothing to do with each other, why it is going further away is because of gravity as einstein described it, in it the eccentricty of earth is slowly changing, when it increase earth is going further away(but also closer) to the sun but this change is rather small. The expansion on earth is rather small, INCREADIBLE SMALL. in this galaxy aswellm, we need to look far away to see the exansions effect