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Stress calculator

A-level Materials

Tensile stress is the force applied to a material divided by its cross-sectional area.

σ = F / A

This free calculator is for A-level physics. Choose the quantity you want to find, enter the other values with their units, and it shows the working in the layout used in exams, with the answer to the number of significant figures you choose. The values shown are an example. Change them to your own.

Quantity to find

6.00 × 108 Pa

Working

  1. Write the equation
    σ = F / A
  2. Substitute the values
    σ = 1200 ÷ (2 × 10−6)
  3. Calculate
    σ = 6 × 108 Pa
  4. Give the answer to 3 significant figures
    σ = 6.00 × 108 Pa

Worked example

Find σ, the stress. Given: force F = 1200 N; cross-sectional area A = 2.00 × 10⁻⁶ m².

  1. Write the equation
    σ = F / A
  2. Substitute the values
    σ = 1200 ÷ (2 × 10−6)
  3. Calculate
    σ = 6 × 108 Pa
  4. Give the answer to 3 significant figures
    σ = 6.00 × 108 Pa

Symbols and units

SymbolQuantitySI unit
σStressPa
FForceN
ACross-sectional aream²

Stress: rearranged

  • To find stress: σ = F / A
  • To find force: F = σ A
  • To find cross-sectional area: A = F / σ

Exam tip

Convert mm² to m² by multiplying by 10⁻⁶. Stress has the same unit as pressure.

Common questions

What is the formula for stress?

The equation is σ = F / A, where σ is the stress (Pa); F is the force (N); A is the cross-sectional area (m²).

What units should I use for stress?

In SI units: stress in Pa, force in N, cross-sectional area in m². The calculator also accepts common alternatives such as kilometres, grams or minutes, and converts them for you.

How do I rearrange σ = F / A?

Rearranging gives these forms: to find stress: σ = F / A. to find force: F = σ A. to find cross-sectional area: A = F / σ.

Practise stress questions

Press the button for a question with random numbers. Work it out on paper first, then type your answer.

Related

More materials equations: Strain, Young modulus. See the full list on the a-level physics equation calculator page.