Stress and plastic deformation: Determine $($a$)$ whether the material will plastically deform and $($b$)$ whether the material will experience necking in the following two cases.

A $850-$lb force is applied to a $0\mathrm{.}15-$in$.$ diameter nickel wire having a yield strength of $45,000$ and a tensile strength of $55,000.(2$ points$)$

A force of $100,000N$ is applied to a $10mm20mm$ iron bar having a yield strength of $400$ MPa and a tensile strength of $480$ MPa $.(2$ points$)$