Situation $2$: The rigid bar ACB is supported by an elastic circular strut $DC$ having an outer diameter of $380mm$ and inner diameter of $365mm.$ The strut is made of steel with a modulus of elasticity of $E=200$GPa. A point load of $P=22kN$ is applied at $B.$

$21.$ Calculate the normal stress in the circular strut $DC.$

a$.9\mathrm{.}40$MPa

c$.4\mathrm{.}90$MPa

b$.9\mathrm{.}04$MPa

d$.4\mathrm{.}09$MPa

$22.$ Calculate the change in length of the circular strut $DC.$

a$.0\mathrm{.}0570mm$

c$.0\mathrm{.}0507mm$

b$.0\mathrm{.}0705mm$

d$.0\mathrm{.}0750mm$