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Strain Calculator

Ratio of extension to original length.

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Strain

Formula first

Overview

Strain represents the physical deformation of a material relative to its original length when subjected to an external force or stress. It is a dimensionless quantity that quantifies how much a body has been stretched or compressed along a specific axis.

Symbols

Variables

= Strain, L = Extension, L = Original Length

Strain
Variable
Extension
Original Length

Apply it well

When To Use

When to use: This formula is used to calculate normal (tensile or compressive) strain in materials within their linear-elastic region. It assumes the deformation is uniform throughout the material and that the original length is used as the reference point.

Why it matters: Understanding strain is essential for predicting structural failure and ensuring the safety of engineering designs like bridges and aircraft. It allows engineers to relate deformation to stress, which is fundamental in defining material properties like the Modulus of Elasticity.

Avoid these traps

Common Mistakes

  • Using total length instead of extension.
  • Mixing cm and m.

One free problem

Practice Problem

A steel cable with an original length of 5.0 meters is stretched by 0.025 meters under a heavy load. Calculate the normal strain experienced by the cable.

Original Length5 m
Extension0.025 m

Solve for: eps

Hint: Strain is the ratio of the change in length to the original length.

The full worked solution stays in the interactive walkthrough.

References

Sources

  1. Beer, F. P., Johnston Jr., E. R., DeWolf, J. T., & Mazurek, D. F. (2015). Mechanics of Materials. McGraw-Hill Education.
  2. Hibbeler, R. C. (2018). Engineering Mechanics: Statics & Dynamics. Pearson.
  3. Wikipedia: Strain (materials science)
  4. Britannica: Strain (physics)
  5. Wikipedia: Strain (mechanics)
  6. Bird, R. Byron; Stewart, Warren E.; Lightfoot, Edwin N. Transport Phenomena. John Wiley & Sons.
  7. Halliday, David; Resnick, Robert; Robert. Fundamentals of Physics. John Wiley & Sons.
  8. Beer, F. P., Johnston Jr., E. R., DeWolf, J. T., & Mazurek, D. F. (2020). Mechanics of Materials (8th ed.). McGraw-Hill Education.