Air is contained in a vertical piston-cyfinder assembly by a piston of mass 50 k

Question

Air is contained in a vertical piston-cyfinder assembly by a piston of mass 50 kg and having a face area of 0. 01 m2. The mass of the air is 5 g, and initially air occupies a volume of 5 liters. The atmosphere exerts a pressure of 100 kPa on top of the piston. The volume of the air slowly decreases to 0. 002 m3 as the specific internal energy of the air decreases by 260 kJ. kg-1. Draw a P-V diagram to illustrate the process and? Explain it. Neglecting friction between the piston and the cyfinder wall, determine the heat transfer to the air in kJ.

Explanation / Answer

Assumptions: g = 9.81 m/s2 No friction Work done by pressure: W = Set up a force balance equation: pApiston = mpistong +patmApiston ; Solve for p: p= = = 149.05 KPa. Work done = (149.05)(.002-.005) = - .44715KJ To find Heat Transfer, Q:Q = W + mair (Uair) Q = - .44715 KJ + .005 kg(-260 KJ) Q = - 1.747KJ

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.