A cylinder contains 1kg of saturated H20 at 30C. This piston has a cross-sectional area of .065m^2, a mass of 40kg, and rests on stops. With the piston in this position, the volume of the H20 is .1m^3. The external atmospheric pressure is 94Kpa and g is 9.75m/s^2. Heat is transferred to the system until the cylinder contains saturated H2O vapor.(adsbygoogle = window.adsbygoogle || []).push({});

1. Sketch the problem on T-v and p-v diagrams.

2. What is the water temperature when the piston just moves off of the stops?

I've been stumped on part 2 for hours. Here's how far I am: The first thing I did was calculate the pressure at which the piston would move up off of the stops. Since at that exact moment the piston won't actually be moving, I can say that Psys*Apiston - Patm*Apiston - m(piston)*g = 0.

Solving, I get Psys = (Patm*Apiston + m(piston)*g)/Apiston. This calculation yields 100KPa.

Help?

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# Homework Help: Thermodynamic Piston problem.

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