Steady-state creep data taken for an iron at a stress level of 139 mpa are given here:
'ϵs(h−1) t(k)
6.6 x 10^−48 1090.
8.8 x 10^−2 1200
if it is known that the value of the stress exponent n for this alloy is 8.4, compute the steady-state creep rate at 1310 k and a stress level of 87 mpa.

Steel balls 12 mm in diameter are annealed by heating to 1150 k and then slowly cooled to 400 k in an air att 325 k and h -20 w/m2 k. assume the properties of the steel to be k- 40 w/m k,p 7800 kg/m3, and cp 600 j/kg k. a. determine whether lumped system method can be used to analyze this problem and if so why" b. determine the time required for the cooling process. c. determine the total amount of heat lost from each ball to the ambient air