Answer to Question #155989 in Mechanical Engineering for rodel

Question

A closed system has 150 KJ of work supplied when the initial volume is 0.6m^3 and pressure of the system changes in the relation p = 8-4V, where V is in m^3 and p is in bar. Compute the final pressure and volume of the system. Express your answer in Pa and m^3

Answer 1

W = nRT ln (p₀/p_f) = pV ln (p₀/p_f)

p = 8 - 4V = 8 - 4 x 0.6 = 5.6 bar

150 x 10³ J = 5.6 x 10⁵ Pa x 0.6 m³ x ln (5.6 x 10⁵ / p_f)

p_f = 3.6 x 10⁵ Pa

3.6 = 8 - 4V_f

V_f = 1.1 m³