Five metal strips, each a $0\mathrm{.}51\mathrm{.}5-in.$ cross section, are bonded

together to form the composite beam shown. The modulus of

elasticity is $30{10}^6$ for the steel, $15{10}^6$ for the brass,

and $10{10}^6$ for the aluminum. The beam is bent about a

horizontal axis by a couple of moment $13$ kip $-$in$.$

Determine the radius of curvature of the composite beam.

The radius of curvature is

ft $.$