$2-$ Two gage marks are placed exactly $10$ in apart on a $1\mathrm{.}0-$in diameter steel rod with ${}_y=50$ksi

and $E=29,000$ksi. The rod is tested under tension until the applied load reaches $P=40$kips

and the distance between the gage marks reaches $10\mathrm{.}05$ in and then unloaded completely.

What is the distance between the gage marks after unloading? Answer: $10\mathrm{.}032$ in$.$