Gravitation Force Exerted by an Extended Object

Question

a. Consider a uniform rod with mass M and length 2L. The rod is placed on the x-axis with its center at the origin. Determine the magnitude of the gravitational force the rod exerts on a point mass M placed at x = 3L.

b. What force will this rod exert on a 2.00 kg point-mass located 0.500 m from the left end? In other words, since the rod is on the x-axis with its ends at x = 0 and x = 1.00 m, then the point mass is on the x-axis at x = −0.500 m.

Answer 1

a) r=3L-x

dF= GM.dm/(3L-x)²

F= GM²/8L²