Just wondering what the rate of gravitational decrease is in a disc - as opposed to a sphere. I know the decrease inside a sphere is at a constant rate g1/r but that once you leave the sphere it then decreases at a squared rate g2/r2. So, while inside a disc at what rate does the gravity decrease if you are moving out from the centre of the disc towards the rim and then when you continue to move away out from the rim? Also, a what rate does the gravity decrease if you move from the centre away from the disc in a direction perpendicular to the disc? Can anyone help me with the answer? Thanks if you can.