4 LAWS OF ENERGY 



In 1798, Count Rumford, who was engaged in boring cannon, 

 showed that the energy of a moving body, i-c kinetic energy, could 

 be transformed into heat. Later, Joule demonstrated the equiva- 

 lence of these two forms of energy. 427 kilogrammetres of work 

 always produce (under standard conditions) one Calorie of heat. 

 Conversely, heat may be transformed into mechanical movement. 

 Indeed, any form of energy may be converted into any other 

 form of energy. (Radio-active matter evolves energy which 

 manifests itself in various forms, yet all attempts to change other 

 forms of energy into radio-active energy or e\'en to influence the 

 rate of transformation have failed. Chap. XIII.) 



TABLE I 



Equivalent Units of Work 



1 Calorie n / 41-9 X 10^ ergs. 



or I ^^jy^^g^i- ' 98-8 X 10^ foot-poiindak. 



l.OUO gram, calories - . - 42-6 X 10^ gram. cms. 



or i ^'^^^ ^ ^^^ foot-lbs. 



10^ microcalories / '4190 joules. 



Equivalent Units op Power 

 1 Calorie per second = 41*9 X 10^ ergs per second, 



= 4-19 X 103 ^.atts. 

 = 4-19 kilowatts. 

 = 5-61 horse-power. 



From observation it is found : 



(1) That one form of energy may be transformed into any 

 other form. 



(2) That when any quantity of energy in any one form dis- 

 appears, an exactly equal quantity of another form of energy 

 makes its appearance. 



Energy like matter is therefore indestructible (First Law of Thermo- 

 dynamics). 



Every substance possesses a certain amount of energy. This 

 is called its internal or intrinsic energy. Further, every group 

 of substances has associated with it a certain definite amount 

 of energy as long as it remains unchanged. When any change 

 takes place in the group, or in any member of the group, there 

 is usually a corresponding change in its total energy, either an 

 increase, due to the reception of energy from its environment, 

 or a decrease, due to an evolution of energy. Put into other 

 words, each of the new substances will have its own characteristic 

 intrinsic energy, and the new group will, in general, have a different 

 total energy-content from that of the original group. 



E.g. Cane sugar + Oo^iC02 -|- HgO + heat energy. 



