Stress (ksi) (1) The Figure below shows the creep rate as a function of stress, for a certain alloy. (a) Determine the working stress at 1100 F and 1500 F using creep strength as the design criteria, based on 1 percent extension in 1000 h. Use a safety factor of 3. (b) Determine the activation energy for creep stress of 10,000 psi 100 5 1100F 0.00001 0.0001 1500 F 1300F 0.01 0.1 0.001 Minimum creep rate (percent per hour) 20070 10 100 prisps er opiu0(a)