P$\mathrm{.}19\mathrm{.}2.$ A wing box has the cross$-$section shown diagrammatically in Fig. P$.19\mathrm{.}2$ and supports a shear load of $100$ kN in its vertical plane of symmetry. Calculate the shear stress at the midpoint of the web $36$ if the thickness of all walls is $2$ mm $.$

Answer: $89\mathrm{.}7$ N$/$mm$^2$

FIGURE P$\mathrm{.}19\mathrm{.}2$

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