A Bimetallic Beam of Aluminum $\left(E_{a}=70 \mathrm{GPa}\right)$ And Copper $\left(E_{c}=110 \mathrm{GPa}\right)$ Strips Has a Width of B = 25 Mm; Each

A bimetallic beam of aluminum $\left(E_{a}=70 \mathrm{GPa}\right)$ and copper $\left(E_{c}=110 \mathrm{GPa}\right)$ strips has a width of b = 25 mm; each strip has a thick- ness t = 1.5 mm. A bending moment of 1.75 N $1.75 \mathrm{~N} \cdot \mathrm{m}$ m is applied about
The z axis. The ratio of the maximum stress in the aluminum to that in the
Copper is approximately: (A) $0.6$
(B) $0.8$
(C) $1.0$
(D) $1.5$