Questions on Newton's Law of Gravitation

[toutou]

hi i have some questions about Newtons law of gravitation and i need complete answers coz these qwestion will be my second exam:
1.the gravitational force between a ring of raduis a and mass m and a rod of mass m and length l lies on the central axis of the ring and the distance is x between them
2.the gravitational force between a disk of raduis a and mass m and a rod of mass m and length l lies on the central axis of the disk and the distance is x between them
by using double integral

 

[robphy]

You'll need to show some work first...as described in https://www.physicsforums.com/showthread.php?t=94379 .

 

[Kurdt]

This is basically the same procedure Dick and I laid out for you in a previous thread. The additional considerations are the geometry of the ring and disk rather than the rod.