During the stress relaxation polymers remain under a fixed strain.
Using the definition of the Relaxation Time constant; "a material property that defines the time needed for the instantaneous stress to decrease to 37% the initial stress", explain why the change in the load is greater at the beginning of the two minutes?

For the closed feedwater heater below, feedwater enters state 3 at a pressure of 2000 psia and temperature of 420 °f at a rate of ix10 ibhr. the feedwat extracted steam enters state 1 at a pressure of 1000 psia and enthalpy of 1500 btu/lbm. the extracted er leaves at an enthalpy of 528.7 btu/lbm steam leaves as a saturated liquid. (16) a) determine the mass flow rate of the extraction steam used to heat the feedwater (10) b) determine the terminal temperature difference of the closed feedwater heater