I don't really understand these questions... Is there anyone who could tell me HOW to solve them? I don't ask about ONLY answers, I just want to understand how to solve these types of exercises.

The things I know:

1. the centrifugal force = the gravitational force

Fg=GmM/r^2

Fc=?

2. the potential =0 (+1 and -1)

5.

and

L>>|SM|, so r~12

sin ~ 0.007

so d*0.007= 1*633

ok but how many interference maxima can be observed?? is there an equation for that?

3. B inside = 0 because it's a sphere...

4 - I have no idea how to do this o.O