# Example Problem with Complete Solution

1D-4 : Identifying a Quasi-Equilibrium Process 4 pts
 Which of the following processes could be reasonably described as a quasi-equilibrium process? a.) a gas escaping from a high-pressure tank through a tiny pin hole into the surrounding air b.) a boy jumping from a cliff into the ocean c.) a woman blowing up a balloon d.) water flowing from the bottom of a large tank through a hose and a shower-head. Read: Not much to say here. Given: a.) Gas escaping from a tank c.) Woman blowing up a balloon b.) Boy jumping from a cliff d.) Water flowing from a tank Find: Can each process be considered to be a quasi-equilibrium process? Assumptions: Equations / Data / Solve: Answers: a.) No. The gas escapes from the high pressure tank very rapidly. The outward pressure force of the gas is not balanced by the pressure force of the surrounding atmosphere. This system deviates substantially from mechanical equilibrium. b.) No. The boy accelerates as he falls because the force of gravity acting on him is not balanced. This system deviates substantially from mechanical equilibrium. c.) Yes. The air from the woman's lungs enters the balloon slowly and steadily in each breath. Acceleration is very modest. Under most circumstances, it would be reasonable to describe this as a quasi-steady-state process. d.) Yes. The tank drains slowly. The water flows slowly and nearly steadily. There are unbalanced forces causing the water to flow from the tank through the tube and the shower head, but the imbalance is modest and the acceleration of the water is very gradual. The pressure at the bottom of the tank decreases as the water level drops. But this occurs slowly. Under most circumstances, it would be reasonable to describe this as a quasi-steady-state process.