Q$3.$ A rigid beam $AB,$ the deformation of which may be neglected, is suspended horizontally from rods $1$ and $2,$ each of which has a circular cross$-$section. Rod $1$ is of steel, and has a diameter of $20$ mm $,$ while rod $2$ is of copper, and has a diameter of $25$ mm $.$ At what distance from the joint $A($see figure$)$ must the load $P$ be applied, if the beam $AB$ is to remain horizonatal after the deformation of the rods? What stresses will then occur in the rods, if $P=3t?$

Answer: $a-1-08m$;$(1)=440k\frac{g}{c}m2$;$(2)=330k\frac{g}{c}m2.$