$7\mathrm{.}2-11$ A rectangular plate of dimensions

$75mm125mm$ is formed by welding two triangular

plates $($see figure$).$ The plate is subjected to a tensile stress

of $3\mathrm{.}5$ MPa in the long direction and a compressive stress

of $2\mathrm{.}5$ MPa in the short direction.

Determine the normal stress ${}_w$ acting perpendicular

to the line of the weld and the shear stress ${}_w$ acting paral$-$

lel to the weld. $($Assume that the normal stress ${}_w$ is posi$-$

tive when it acts in tension against the weld and the shear

stress ${}_w$ is positive when it acts counterclockwise against

the weld.$)$

PROB. $7\mathrm{.}2-11$