m x ¨ + b x ˙ − k ( f − x ) = 0 {\displaystyle m{\ddot {x}}+b{\dot {x}}-k(f-x)=0}
x ¨ + b m x ˙ + k m x = k m f {\displaystyle {\ddot {x}}+{\frac {b}{m}}{\dot {x}}+{\frac {k}{m}}x={\frac {k}{m}}f}
