7.4-18 through 7.4-25 An element in plane stress
is subjected to stresses $\sigma_x$, $\sigma_y$, and $\tau_{xy}$ (see figure).
Using Mohr's circle, determine (a) the principal
stresses and (b) the maximum shear stresses and asso-
ciated normal stresses. Show all results on sketches of
properly oriented elements.
$\sigma_x = 2900 \text{ kPa}$, $\sigma_y = 9100 \text{ kPa}$, $\tau_{xy} = -3750 \text{ kPa}$