A magnesium oxide component must not fail when a tensile stress of 14 MPa is applied. Determine the maximum allowable surface crack length if the surface energy of magnesium oxide is 1.0 J/m2. The modulus of elasticity of this material is 225 GPa.

Consider a 1.2 meter high and 2 meter wide glass window whose thickness is 6 mm and thermal conductivity is 0.78 w/m °c. the room temperature is maintained at 24 °c, while the outdoor temperature is -5 °c. the convective heat transfer coefficients on the inner and outer surfaces of the window are 10 w/m2 °c and 25 w/m2 °c respectively. (a) draw the thermal resistance network, etermine the steady rate of heat transfer t e glass window (c) determine the temperature of the inner surface of the window