Final answer:
The question pertains to engineering principles of tensile and compressive stresses, where forces either stretch or squeeze an object, respectively. Small deformations keep change in length the same under tension or compression, but larger deformations alter cross-sectional areas. Equilibrium and material science concepts are utilized for calculations.
Step-by-step explanation:
Tension and Compression
The question relates to fundamental concepts of mechanical engineering, specifically the responses of materials under tensile stress and compressive stress. Tension occurs when forces are applied in opposite directions along the length of an object, attempting to stretch it. Compression is the opposite, where forces push towards each other, attempting to shorten the object.
For very small deformations and uniform materials, the change in length (ΔL) remains approximately the same under equal magnitudes of tension or compression. However, for larger deformations, the nature of the change can impact the cross-sectional area, either stretching it thinner or compressing it to be wider.
Regarding the numerical problems such as reactions, forces, and stretches, these are typically determined through equilibrium equations in statics and dynamics, as well as concepts from the material science field, like Hooke's Law for springs and stress-strain relationships for materials.