An insulated rigid tank initially contains 1.8 Ibm of helium at 82 F and 45 psia. A paddle wheel with a power rating of 0.025 hp is operating within the tank for 45 minutes. The specific heat at constant volume (cv) for helium is 0.753 BTU/(Ibm-•F). Determine the:
a) amount of paddle-wheel work in BTU after 45 minutes
b) final temperature
c) final pressure of the helium gas Ans. P2 = 47.92 psi