A specimen of an isotropic, linear elastic material with Young's modulus E and is placed inside a rigid box that prevents the material from stretching in any direction. This means that the strains in the specimen are zero. The specimen is then heated to increase its temperature by ΔT. Find a formula for the stress in the specimen. Find a formula for the strain energy density. How much strain energy would be stored in a 1cm³ sample of steel if its temperature were increased by 100C? Compare the strain energy with the heat required to change the temperature by 100c – the specific heat capacity of steel is about 470 J/(kg-C).