358 ON PHYSICAL DATA 



Hence, the two particles M and M' will ap- 

 proach, be at rest, or recede from each other, 

 according as the following conditions are complied 

 with respectively, namely. 



~2|-^>«''¥-^ (15) 



= m'-^ (16) 



"^<-'^^ (17) 



These equations reduce to the following, 



mf(a:) >m' <i>{x) (18) 



m{(x) = m'^(x) (19) 



m {(x) <m' <i>(x) (20) 



If the condition (18) is complied with we shall 

 have ~s!^^ — — =■ the effective attractive 

 force of A on B (21) 



And if the condition (19) is complied with we 

 shall have -^ = ^J^ (22) 



And if the condition (20) is fulfilled we shall 

 have ^- — 3 " = the effective repulsive 

 force of A on B (23) 



