As temperature increases, what happens to the modulus of elasticity?

• A. Increases
• B. Decreases
• C. Stays constant
• D. First increases then decreases

Answer: (B)

As temperature increases, the stiffness of a material generally drops, so the modulus of elasticity decreases. Higher thermal energy causes atoms to vibrate more and bond forces to act less rigidly, which lowers the curvature of the potential energy that defines elastic response. In practical terms, the slope of the elastic portion of the stress–strain curve becomes smaller at higher temperatures, meaning the material is less stiff. This trend is common for metals and many ceramics, while polymers often show an even more pronounced decrease with temperature. Anomalies can occur near phase transitions, but the usual trend is a decrease with rising temperature.