Non-minimum phase systems are defined as those in which the transfer function has a positive zero, i. e., a root of the numerator is greater than zero. with these types of systems, it is notoriously difficult to achieve good feedback control performance. why?

Acircular aluminum shaft mounted in a journal is shown. the symmetric clearance gap between the shaft and journal is filled with sae 10w-30 oil at t 30°c. the shaft is caused to turn by the attached mass and cord. develop and solve a differential equation for the angular speed of the shaft as a function of time.