Topic: Strength of Materials
A bar of copper and steel together forms a composite system are heated to a temperature of $40^{\circ}C$. What type of stress is induced in the copper bar?
- A. Tensile
- B. Compressive
- C. Shear
- D. Tensile as well as compressive
Answer: B. Compressive
Explanation: Copper has a higher coefficient of thermal expansion ($\alpha$) than steel. When heated, the copper bar attempts to expand more than the steel bar. The composite nature forces them to expand by the same amount, meaning steel restricts the free expansion of copper. As a result, the copper bar experiences compressive stress, and the steel bar experiences tensile stress.