PARAMETERS 



6/3 



may be ignored ; but the relationship of an effective parameter 

 to a system must be clearly understood. 



Given a system, the effective parameters are usually innumer- 

 able, so that a list is bounded only by the imagination of the 

 writer. Thus, parameters whose change might affect the be- 

 haviour of the same system of two variables are : 



(1) the length of the pendulum (hitherto assumed constant), 



(2) the lateral velocity of the air (hitherto assumed to be 



constant at zero), 



(3) the viscosity of the surrounding medium (hitherto assumed 



constant), 



(4) the position (co-ordinates) of the point of support, 



(5) the force of gravity, 



(6) the magnetic field in which it swings, 



(7) the elastic constant of the string of the pendulum, 



(8) its electrostatic charge, and the charges on bodies nearby ; 

 but the list has no end. 



Parameter and field 



6/3. The effect on an absolute system of a change of parameter- 

 value will now be shown. Table 6/3/1 shows the results of four 



Table 6/3/1. 

 73 



