A plate in equilibrium is subjected to uniform stresses along its edges with magnitude $\sigma_{x x}=30 \mathrm{MPa}$ and $\sigma_{y y}=50 \mathrm{MPa}$ as shown in the figure.
The Young's modulus of the material is $2 \times 10^{11} \mathrm{~N} / \mathrm{m}^{2}$ and the Poisson's ratio is 0.3 . If $\sigma_{z z}$ is negligibly small and assumed to be zero, then the strain $\varepsilon_{z z}$ is
(A) $-120 \times 10^{-6}$
(B) $-60 \times 10^{-6}$
(C) 0.0
(D) $120 \times 10^{-6}$
A plate in equilibrium is subjected to uniform stresses along its edges with magnitude $\sigma_{x x}=30 \mathrm{MPa}$ and $\sigma_{y y}=50 \mathrm{MPa}$ as shown in the figure.
The Young's modulus of the material is $2 \times 10^{11} \mathrm{~N} / \mathrm{m}^{2}$ and the Poisson's ratio is 0.3 . If $\sigma_{z z}$ is negligibly small and assumed to be zero, then the strain $\varepsilon_{z z}$ is
(A) $-120 \times 10^{-6}$
(B) $-60 \times 10^{-6}$
(C) 0.0
(D) $120 \times 10^{-6}$