Question: The frequency response of a system can be determined empirically by introducing a sine to an input variable, waiting until the initial transient is negligible, and measuring the input and output amplitudes and the phase angle. If this procedure were performed for several input frequencies, how could you determine whether the real physical system were first-order or second-order? After selecting the proper transfer function order, how could you determine the unknown parameters, gain, and time constant(s)? Also, discuss possible limitations to this empirical method.