Stress, strain and Young's modulus: the three calculations that drive every Unit 3 materials question

What this note covers

1. Stress divides the load by the area that carries it
2. Strain is a ratio, not an extension with a new name
3. Young’s modulus is the elastic slope
4. Predict extension while keeping units and assumptions visible
5. Separate modulus, yield and ultimate tensile strength
6. Interpret measurements and write a reliable calculation chain
7. Worked tensile-test chain: stress, strain, modulus and extension
8. Worked uncertainty check: why diameter measurement controls stress

8 sections · 10 key terms & formulas · 6 common mistakes