Stress at any point in a material is defined as
- Aload per unit area
- Bresisting force per unit areaCorrect
- Cmodulus elasticity times strain
- Dnone of the above
Solution
Concept
Definition of stress
Formula
σ = P / A
Step-by-step solution
1. Stress is the internal resisting force developed in a body per unit area of cross-section. 2. Under equilibrium the resisting force equals the applied load, so both are used in practice, but the formal definition is the resisting force per unit area.
Explanation
Stress is the intensity of the internal resisting force on a section, measured as force per unit area. It is the response of the material to the applied load.
Why the other options are wrong
Load per unit area (A) describes the applied intensity, not the internal resistance. Modulus times strain gives stress only in the elastic range, so it is not the definition.
Shortcut
Stress = internal resisting force ÷ area.
Common mistake
Choosing "load per unit area".
Correct answer: B) resisting force per unit area