Example

Two gage marks, $2\mathrm{.}000-$in apart, are made on a copper alloy specimen $($Fig$.$ A$).$ The specimen is loaded slowly and the yield point is noted: ${}_y=45$ksi,${}_y=0\mathrm{.}0025.$ When a stress of $70$ ksi is reached during the test at a strain of $0\mathrm{.}40$ the specimen is unloaded. Determine the distance between the gage marks after testing $($Fig$.$ C$).$