mobility

6.79  mobility. Analogous mobilities are defined as the ratios of the following complex amplitudes:

• mechanical mobility              Z_M =velocity across/force through;
• rotational mobility    Z_R =angular velocity across/torque through;
• acoustic mobility      Z_A =volume velocity across/sound pressure through;
• electric impedance Z =voltage across/current through.
• The real part of each mobility is called responsiveness and the imaginary part the excitability. The reciprocal on any mobility is an immobility whose real part is unresponsiveness and imaginary part is unexcitability.