... dz dt - = CZ, -d 211 =C dx" d 1+ ( 2 - , Figure 1, Electrical circuit, (6) equation (2) Equation (1) is the differential equatio11governing the linear displacement z ( t ... The independent variable is t in (1) -(4) and x in (5) and (6) Some representative and i~nportantpartial differential equations (PDE's) are as follows: a u 8 21 C U 2= (7) dz-t ' x Figure Hanging ... ordinary derivatives with respect to a single independent variable, and as a partial differential equation if it contains partial derivatives with respect to two or more independent variables Thus,...