8.42 Steady-state creep rate data are given in the + following table for some alloy taken at 200°C (473 K): és (h-¹) 2.5 × 10-3 2.4 × 10-2 σ[MPa (psi)] 55 (8000) 69 (10,000) If it is known that the activation energy for creep is 140,000 J/mol, compute the steady-state creep rate at a temperature of 250°C (523 K) and a stress level of 48 MPa (7000 psi).