40 OUTLINES OF NATURAL PHILOSOPHY. 



The velocity of-C is A + ^ + c *v 

 4f A a , , 



. p rt 



lono 



4 AC a 



If the number of the bodies in geometrical progres- 

 sion be increased without limit, the quantity of 

 motion communicated to the last, from a given 

 quantity of motion in the first, however small, may 

 also be increased without limit. Notwithstanding 

 this, as all the bodies move backward after collision 

 but the last, if they form an increasing series, the 

 sum of all the motions in the direction of the first 

 mover continues = A a. Also the sum of the pro- 

 ducts of each body, into the square of its velocity, 

 after collision, remains as it was before, equal to 



82. If an elastic body strike against an im- 

 moveable plane, it will be reflected from it, so that. 

 its direction before and after collision will make 

 equal angles with the plane, but toward opposite 

 sides. 



If the elastic body strike on the plane CD (fig. 5.) in 

 the direction AB, it will be reflected in the di- 

 rection BE, so that the angles ABC, EBD shall be 

 equal. 



83. If 



