Final answer:
To find the displacement of end A of the composite rod, apply Hooke's Law to each material section and sum the displacements.
Step-by-step explanation:
The displacement of the end A of a composite rod subjected to axial loadings can be determined using Hooke's Law for each material and adding the displacements due to each segment. For steel rod CB and aluminum rod BA, the formula ΔL = FL / (AE) (where L is the length, F the force applied, A the cross-sectional area, and E the modulus of elasticity) can be used to find the individual displacements caused by the axial load F. Combining both displacements gives the total displacement at point A. Assuming a uniform cross-sectional area and material properties, along with small deformations, allows us to ignore changes in the cross-sectional area due to the load.