

irf, and supposing the asvnptotes of an hyper- 

 10 consist of such i ahew that a particle Y, 



brium at a of the hyjwrbola, and that the 



int M proportion) t - the length of the 



attracts an internal particle x, y) 



with a force varvi rsely as the distance; shew that if 



whole attractions parallel to the axe*, 



- constant 



y 



It be the attractions of an ellipsoid in direc- 



- axes on an internal particle situated at the 

 t (/, y, A), shew that 



/? C 

 f+I 



resultant attraction of a particle which attracts 

 linj; to tin- iiiNTso culx- of the distance on a plane 

 .1 is the same as on that part of the spherical 



[described about the particle as centre and touching the plane 

 lamina, which is cut off by straight lines from 



kentre to the edge of the lamina. 



attracted by two centres of force at A and 

 placed in a fixed groov* that the particle re- 



rest at whatever point it is placed, provided that 

 i m of the groove be such that 



c, c' are constants dependent upon the absolute forces. 



17. I ; a portion of a thin spherical shell, whose projections 



three co-ordinate planes through the centre are 



C, attract a particle at the centre with a force varying 



distance, shew that the panicle will 



move in the direction of the straight line whose equa- 







m f 



212 



