Stress relaxation: A stress of 1.5 MPa was required to stretch a 3-cm long aorta strip to 3.4 cm. After 2 hours in the same stretched position, the strip exerted a stress of 1.2 MPa. Assume the mechanical property of the aorta did not vary appreciably during the experiment. a) What is the relaxation time, assuming a simple exponential decay model? b) With the aorta strip staying in the same stretched position for the initial two hours, how much more time has to go past, for the stress exerted by the aorta strip to reach a value of 1.1 MPa? Please indicate time in hours: minutes.