1. Air is contained in a piston-cylinder assembly oriented horizontally as shown

Question

1. Air is contained in a piston-cylinder assembly oriented horizontally as shown in the figure below. The air cools from an initial volume of Vir=0.003 m3 to a final volume of vg= 0.002 m3. During the process, the spring exerts a force that varies linearly from an initial value of F-900N to a final value of F 0. The atmospheric pressure is Pam 100kPa, and the cross- sectional area of the piston is A 0.018m2. Friction between the piston and the cylinder wall can be neglected (a) (b) (c) Find the initial pressure of air, p, in kPa. Find the final pressure of air, p2, in kPa Find the work, WT, in kJ. (d) What does the sign of WT imply about the direction of energy transfer as work in this problem? A-0.018 m2 Patm-100 kPa Air Spring force varies linearly from 900 N when 0.003 m' to zero whe 0.002 m

Explanation / Answer

Initial Volume of Air: V1 = 0.003 m3
Final Volume of Air: V2 = 0.002 m3

Spring Pressure:

Intial Pressure: F1 = 900 N
Final Pressure: F2 = 0 N

Atmospheric Pressure = 100 kPa, Cross-sectional Area: A = 0.018 m2

We know that spring force varies linearly from 900 N when V1 = 0.003 m3 to zero when
V2 = 0.002 m3 that means spring is at equilibrium condition when volume of air is 0.002 m3.

Then, initially force applied by air to piston at volume 0.003 m3 is 900 N.

P1 = force applied to the piston by air/A + Patm

P1 = 900/0.018*0.001 + 100 (0.001 is conversion factor for N/m2(Pa) to kPa)

P1 = 150 kPa

P2 = 0 + 100

P2 = 100 kPa

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

---

---

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