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Required information

Two solid cylindrical rods $AB$ and $BC$ are welded together at $B$ and loaded as shown. Knowing that the magnitude of the average normal stress must not exceed $155$ MPa in either rod, determine the smallest allowable values of the diameters d $1$ and d $2.$ Take $P=50kN$ and $Q=125$ kN $.$

Jsing FBDs$/$equilibrium equations for ABC, cut sections between $A$&$B$ and between &$C,$ determine the

magnitude of the internal reaction force $P_{AB}=$ kN $.$

magnitude of the internal reaction force $P_{BC}=$ kN $.$