3 ms·
Have you noticed people misapplying that to galaxies? They'll claim there is no influence on a star due to the part of the disk at greater radius, and also that
by phkahler 3y ago
Have you noticed people misapplying that to galaxies? They'll claim there is no influence on a star due to the part of the disk at greater radius, and also that the mass inside that radius can be treated as a point mass. But disks are not spheres, and rings are not shells, so those simplification do not apply. I've seen this mistake many times.
- somewhereoutth 3y agoInteresting question. Given n stars/whatever at varying positions, is there always at least one point where the gravitational forces cancel out? Or is that just a solution to the simple cases of two bodies or a single body in the form of a sphere or shell?
- dangond 3y agoI can't do the math to determine this more rigorously, but my intuition tells me you can do something analogous to the Hairy Ball Theorem to prove that there exists a point within the convex hull of those stars where the gravitational forces cancel out. However, as the stars move, there's no guarantee that point will remain static and stable.