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In mechanics of materials, what is stress?

Force per unit area, measured in pascals.

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  1. The total force on a part
  2. Force per unit area ✔
  3. The change in length per unit length

Why: Stress lets you compare a thin wire and a thick bar fairly. The same force in a smaller cross section gives higher stress, which is what makes parts fail.

Huh, didn't know that: Change in length divided by original length is strain, stress's partner.

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My bridge is under a lot of stress, but at least it's spread over a big area.
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References

Answer: Force per unit area. Stress lets you compare a thin wire and a thick bar fairly. The same force in a smaller cross section gives higher stress, which is what makes parts fail.

  1. OpenStax University Physics Volume 1: 12.3 Stress, Strain, and Elastic Modulus openstax.org/books/university-physics-volume-1/pages/12-3-stress-strain-and-elastic-modulus
    Stress is generally defined as force per unit area
    Checked 2026-10-11.
  2. OpenStax University Physics Volume 1: 12.3 Stress, Strain, and Elastic Modulus openstax.org/books/university-physics-volume-1/pages/12-3-stress-strain-and-elastic-modulus
    The SI unit of stress is the pascal (Pa).
    Checked 2026-10-11.

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