A solid round bar of AISI 1018 cold-drawn steel is used as a torsion bar and subjected to a reversing torque of 200 Nm. The bar is 25mm in diameter and has a machined groove 2.5mm in depth with a 2.5mm fillet radius that is used for axial location. Determine the expected life of the torsion bar.

10 kg of co2 is initially contained at 400 kpa and 300 k. the gas constant for carbon dioxide is 189 j/lkg k) and has a specific heat ratio, k, of 1.289. isentropic expansion then occurs until the pressure is 200 kpa. a) determine the initial volume of co2 in m. b) determine the final temperature in k. c) determine the work done by the system during the expansion kl.