A steel bar has a rectangular section $3050mm$ and is $600$ mm in length.

Determine the strain energy stored in the bar when it is subjected to an axial load of $200$ kN $.$

If the bar reaches its elastic limit when the axial load is $465$ kN $,$ what is the proof resilience of the steel?

E for steel is $210$ GPa $.$

$(38\mathrm{.}095$ kJ$,228\mathrm{.}8$ kJ $)$