A stainless steel rod of diameter 12 mm and length 2.5 m is kept on frictionless surface and heated from 300 K to 400 K. What is the thermal stress on the rod? (coefficient of linear expansion of the steel may be taken as $$10^{–5}/K$$​; yield strength of steel as 200 MPa and Young’s modulus as 210 GPa) 

Correct option is D

​​​$$\textbf{Concept:}\\\text{{Thermal stress in a rod is developed only when its thermal expansion is }\\\textbf{restricted}. The formula is:\\}\\\sigma_{\text{thermal}} = E \alpha \Delta T\\\text{Here, the stainless steel rod is placed on a \textbf{frictionless surface}, hence its expansion is \textbf{not restricted}. Therefore, no thermal stress will be induced.}\\\sigma_{\text{thermal}} = 0 \ \text{MPa}$$​​