• question_answer At $15{}^\circ C,$ a wheel has diameter of 30 cm and inside diameter of a steel rim is 29.9 cm. Coefficient of thermal expansion of steel is $1.2\times {{10}^{-5}}{{/}^{o}}C$. To what temperature, the rim must be heated so that it can slip over wheel? A) $2787{}^\circ C$                     B) $2772{}^\circ C$ C) $2529{}^\circ C$                     D) $2802{}^\circ C$

 Rim will slip if its diameter increases to 30 cm. Hence $\Delta l=0.1\,cm$ $\Delta T=\frac{\Delta l}{l\times a}=\frac{0.1}{29.9\times 1.2\times {{10}^{-5}}}={{2787}^{o}}C$ Rim to be heated to temperature $2787+15={{2802}^{o}}C$