• id: JME-08-N04
• title: Hooke's Law
• tags: hooke, proportionality, elastic-limit

Robert Hooke (1676) stated that within the elastic limit, stress is directly proportional to strain: $\sigma = E\varepsilon$, where $E$ is the modulus of elasticity. This is valid only up to the proportional limit on the stress-strain curve. Beyond this point, the material may still be elastic (up to the elastic limit) but the relationship is no longer linear. Hooke's Law is not a fundamental law — it is an empirical observation that works well for most engineering materials under small deformations.