366 



VIIL NEWTONIAN POTENTIAL FUNCTION. 



126. Disc, Cylinder, Cone. Let us find the attraction of a 

 circular disc of infinitesimal thickness at a point on a line normal 

 to the disc at its center. Let the radius be R, thickness a, distance 

 of P from the center In. 







= 2xeQ{yh 2 + R 2 -h], 



Attraction of circular cylinder on 

 point in its axis. Let the length be I 

 and let the point be external, at a 

 distance Ji from the center. 



By the above, a disc of thickness 

 dx at a distance x from the center 

 produces a potential at P 



-x} 2 -(h- x)}. 



Hence the whole is 



84) V- 



Circular cone on point in axis. 



