A gas mixture with volumetric proportions of 30%, carbon dioxide (specific heat of 0.867 kJ/kg-K) and 70% nitrogen (specific heat of 1.043 kJ/kg-K) is cooled at constant pressure from 150oC to 50oC. What is most nearly the energy released as heat per unit mass of mixture?

Ahelical coil spring has a mean diameter of 50 mm, a wire diameter of 5.5 mm and is wound with a pitch of 10 mm. the spring steel has an ultimate strength of 1250 mpa. find the force needed to compress the spring solid and the wire stress in this condition. state whether the spring will return to its initial length.