Basic definition in mechanics of materials: when a body is pulled by two equal and opposite forces and tends to increase in length, what are the resulting stress and strain called?

Introduction / Context:
This question checks your understanding of the core terminology in strength of materials: identifying the type of stress and strain under axial pulling (tension).

Given Data / Assumptions:

• A straight member is subjected to two equal and opposite axial pulls.
• Forces act along the member’s axis and try to elongate it.
• Material response is within the elastic range for clarity.

Concept / Approach:
Stress is internal resistance per unit area. When axial forces pull the material outward and it tends to lengthen, the normal stress developed is tensile. The corresponding deformation is an increase in length, i.e., tensile strain (positive linear strain).

Step-by-Step Solution:

Verification / Alternative check:
If the same member were pushed (shortened), we would describe the state as compressive stress with compressive strain. Here we explicitly have extension, confirming tensile–tensile.

Why Other Options Are Wrong:
Compressive pairings contradict the observed extension.Tensile stress with compressive strain is inconsistent with axial pulling.Shear stress–strain applies to tangential loading, not axial pull.

Common Pitfalls:
Confusing sign conventions for strain; tensile strain is positive elongation, compressive is negative shortening.

Final Answer:

tensile stress, tensile strain