The assembly consists of two posts $A B$ and $C D$ each made from material 1 having a modulus of elasticity of $E_1$ and a cross-sectional area $A_1$, and a central post made from material 2 having a modulus of elasticity $E_2$ and crosssectional area $A_2$. If a load $\mathbf{P}$ is applied to the rigid cap, determine the force in each material.