ONE DEGREE OF FREEDOM 55 



inertance M comprising the air in the tubular opening which is connected 

 to the volume Ca. The acoustical resistance Ta is due to radiation. 



A. Kinetic Energy. — The kinetic energy, in ergs, stored in the mag- 

 netic field of the electrical circuit is 



Ike = 2'-'^ ^. 1 / 



where L = inductance, in abhenries, and 



i — current through the inductance L, in abamperes. 

 The kinetic energy, in ergs, stored in the mass of the mechanical 

 system is 



Tkm = hmx" 4.18 



where m = mass, in grams, and 



X = velocity of the mass m, in centimeters per second. 

 The kinetic energy, in ergs, stored in the inertance of the acoustical 

 system is 



TKA = hMX^ 4.19 



where M = m/ S"^, the inertance, 



m — mass of air in the opening, in grams, 

 S = cross-sectional area of the opening, in square centimeters, 

 X = Sx, and 



X = velocity of the air particles in the opening, in centimeters per 

 second. 

 It is assumed that all the air particles in the opening move with the 

 same phase. 



B. Potential Energy. — The potential energy, in ergs, stored in the 

 electric field of the electrical circuit is 



1 <7^ 

 ^p^ = -^7r 4.20 



where Ce = capacitance, in abfarads, and 



5/ = charge on the capacitance, in abcoulombs. 



The potential energy, in ergs, stored in the compliance or spring of the 



mechanical system is 



1 x'^ 

 ^PE = -'^ 4.21 



where Cm = lA, compliance of the spring, in centimeters per dyne, 

 s = stiffness of the spring, in dynes per centimeter, and 

 X = displacement, in centimeters. 



