THE ENERGY CONCEPT OF LIFE 

 II II 



13 



Mutationem motus proportio- 

 nalem esse vi motrici impressae, et 

 fieri secundum lineam rectam qua 

 vis ilia imprimitur. 



Ill 



Actioni contrariam semper et 

 aequalem esse reactionem: sive cor- 

 porum duorum actiones in se mutuo 

 semper esse asquales et in partes 

 contrarias dirigi. 



The alteration of motion is ever 

 proportional to the motive force 

 impressed; and is made in the direc- 

 tion of the right line in which that 

 force is impressed. 



Ill 



To every action there is always 

 opposed an equal reaction: or the 

 mutual actions of two bodies upon 

 each other are always equal, and 

 directed to contrary parts. 



Newton's third law of the equahty of action and reaction is 

 the foundation of the modern doctrine of energy,^ not only in 

 the Newtonian sense but in the most general sense.- Newton 

 divined the principle of the conservation of energy in mechanics; 

 Rumford (1798) maintained the universality of the laws of 

 energy; Joule (1843) established the particular principle of the 

 conservation of energy, namely of the exact equivalence be- 

 tween the amount of heat produced and the amount of mechan- 

 ical energy destroyed; and Helmholtz in his great memoir 

 Uher die Erlialtiing dcr Kraft extended this system of conser- 

 vation of energy throughout the whole range of natural phe- 

 nomena. A familiar instance of the so-called transformation of 

 energy is where the sudden arrest of a cool but rapidly moving 

 body produces heat. This was developed as the first law of 

 thermodynam ics. 



At the same time there arose the distinction between po- 

 tential energy, which is stored away in some latent form or 

 manner so that it can be drawn upon for work — such energy 



> The lerm Energy (Gr. svspYsta; sv in; epyov, work) in physical science denotes an 

 accumulated capacity for doing mechanical work, and may be either kinetic (energy of 

 heat or motion) or potential (latent or stored energy). 

 - M. I. Pupin, see note above. 



