An aluminum alloy that has a plane strain fracture toughness of 25,000 ps  fails when a st...

An aluminum alloy that has a plane strain fracture toughness of 25,000 ps  fails when a stress of 42,000 psi is applied. Observation of the fracture surface indicates that fracture began at the surface of the part. Estimate the size of the flaw that initiated fracture. Assume that f = 1.1.