Practice problem: true stress and strain a cylindrical specimen of a metal alloy 49.9 mm long and 9.72 mm in diameter is stressed in tension. a true stress of 376 mpa causes the specimen to plastically elongate to a length of 53.5 mm. if it is known that the strain-hardening exponent for this alloy is 0.1, calculate the true stress (in mpa) necessary to plastically elongate a specimen of this same material from a length of 49.9 mm to a length of 58.2 mm.

Amass of m 1.5 kg of steam is contained in a closed rigid container. initially the pressure and temperature of the steam are: p 1.5 mpa and t 240°c (superheated state), respectively. then the temperature drops to t2= 100°c as the result of heat transfer to the surroundings. determine: a) quality of the steam at the end of the process, b) heat transfer with the surroundings. for: p1.5 mpa and t 240°c: enthalpy of superheated vapour is 2900 kj/kg, specific volume of superheated vapour is 0. 1483 m/kg, while for t 100°c: enthalpy of saturated liquid water is 419kj/kg, specific volume of saturated liquid water is 0.001043m/kg, enthalpy of saturated vapour is 2676 kj/kg, specific volume of saturated vapour is 1.672 m/kg and pressure is 0.1 mpa.