# Math Help - Computing total attractive force by integrating over the surface of the shell S.

1. ## Computing total attractive force by integrating over the surface of the shell S.

It would be really appreciate if someone can explain what to do on this question.

Thank you.

2. ## Re: Computing total attractive force by integrating over the surface of the shell S.

I would first calculate the force due to a small "ring" of the spherical shell - it is a constant distance from the point mass at (0,0,b). Then integrate to get the total force.

I won't ruin the ending for you, except to say that you'll be surprised at what the force *doesn't* depend on.

- Hollywood