(the "T"'s are tau's)

A process has the transfer function of G(s)=(K*(Ta*s+1)) / ((T1*s+1)*(T2*s+1)). It has values K=2, T1=10, and T2=2.

A) If Ta has the following values, case i: Ta=20, case ii: Ta=4, case iii: Ta=1, case iv: Ta=-2, then plot the composite amplitude ratio amd phase angle curves on a single Bode plot for each case. What can you conclude concerning the importance of the zero location for the amplitude and phase characteristics of this second order system?

B) Of the four cases, which one(s) will be susceptible to an instability if the proportional control is used with too large of a controller gain, and why?