Alarge nickel plate, 1 mm thick, is heated on both sides by flowing air and loaded in tension to one-half of its failure stress. laboratory tests on small nickel plates, carried out under operating conditions, give a parabolic rate constant of 109 kg2 m4 s1 a) use dimensional analysis to work out how the rate constant given relates to other parameters b) what thickness would need to be oxidised way on each face for the plate to reach its failure stress, assuming that the oxide formed can support no load? estimate the maximum lifetime of the plate under these conditions. during operation, it is observed that the oxide layer spalls off approximately every month. why might this be expected? in the light of this, modify your estimate of the lifetime. c) d)