Physics

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Elongation Calculator.

Calculate axial elastic elongation of a uniform bar.

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01

Set your values

Results update as you type.

Elongation: 0.00005

Elongation

0.000000
Strain: 0.00005

Strain

0.000000

Educational SI model using the assumptions stated above; verify engineering and safety decisions independently.

Use Cases

Engineering design and analysis

Engineers can use this calculator to predict how much a structural member will stretch under a given axial load, ensuring designs stay within safe elastic limits.

Example: Calculate elongation of a steel rod (E=200 GPa) with length 2 m, area 0.01 m², under 50 kN force.

Educational demonstrations

Physics and engineering students can quickly compute elongation for various materials and loads to understand Hooke's law and elastic deformation.

Example: Compare elongation of aluminum vs. steel bars under the same load.

Frequently Asked Questions

What is axial elastic elongation?
Axial elastic elongation is the increase in length of a bar when subjected to an axial force within its elastic limit. It is calculated using the formula: elongation = (axial force × original length) / (cross-sectional area × Young's modulus).
What units should I use for the inputs?
Use newtons (N) for axial force, meters (m) for original length, square meters (m²) for cross-sectional area, and pascals (Pa) for Young's modulus. The calculator will output elongation in meters.
Can this calculator be used for any material?
Yes, as long as the material behaves elastically and you know its Young's modulus. The calculator assumes uniform cross-section and axial loading, and it is valid only within the elastic limit of the material.

Tips & Common Mistakes

Tips

  • Ensure all input values are in consistent SI units: N, m, m², and Pa. Convert if necessary.
  • Use the material's Young's modulus from reliable sources; it varies with temperature and alloy composition.
  • This calculator assumes uniform cross-section and axial loading. For non-uniform bars, more complex analysis is needed.
  • Check that the calculated elongation is small relative to the original length; if not, the material may be beyond its elastic limit.

Common Mistakes to Avoid

  • Mixing units, e.g., using mm for length and m² for area, which leads to incorrect results.
  • Using the yield strength instead of Young's modulus; Young's modulus is a material property, not a stress limit.
  • Forgetting that the cross-sectional area must be in square meters; using cm² or mm² without conversion.

Last updated: August 13, 2026