An inventor claimed that a cyclic engine produces 0.4 kj of work per kj of heat extracted from a heat reservoir. a)- the cycle operates between 380 °c and 25 °c. is the claim valid? b)- if the cycle operates between 380 °c and 125 °c, would the claim be valid?

Along steel shaft of 10 cm diameter is austenised at 870°c and then quenched in a liquid at 30oc. the average surface heat transfer coefficient is 2000 w/m2. °c. the relevant thermophysical properties of the shaft are: p=7800 kg/m", k=20 w/mk, cp=0.46 kj/kg. k calculate: a)-the time required for the center temperature to drop to 200°c. b)-the temperature at half-radius at that moment. c)-the amount of heat that had been transferred to the liquid by that time per meter length of the shaft