What is the magnitude of the maximum stress that exists at the tip of an internal crack having a radius of curvature of 2.5×10-4 mm (0.9843×10-5 in.) and a crack length of 4×10-2 mm (1.575×10-3 in.) when a tensile stress of 100 MPa (14500 psi) is applied?

Air inially occupying a volume of 1 m2 at 100 kpa, 27 c undergoes three internally reversible processes in series. process 1-2 compression to 500 kpa during which pv constant process 2-3 adiabatic expanslon to 100 kpa process 3-1: constant-pressure expansion to 100 kpa (a) calculate the change of entropy for each of the three processes. (b) calculate the heat and work involved in each process. (c) is this cycle a power cycle or refrigeration cycle?