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## Homework Statement

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An insulated cylinder containing water has a piston held by a pin. The water is initially saturated vapour at 65°C and a volume of 5L. The piston has a total mass of 10kg, its area is 0.003 m^2 and the atmospheric pressure is 100kPa. The pin is then released, allowing the piston to move. Determine the final pressure and temperature of the water assuming the process to be adiabatic.

## Homework Equations

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Sum of forces = 0

F = PA

W = mg

## The Attempt at a Solution

At equilibrium:

P2 *A = mg + Patm *A

P2 = mg/A + Patm = 10*9.8/0.003 + 100*10^3 = 132666.6667 Pa = 1.326666667 bar

That's the first part done. Now I'm stuck at the second part - finding the final temperature of the water (T2). This is what I've got so far:

V1 = 5 L = 0.005 m^3 (given)

v1 = 6.201 m^3/kg (using the Steam Table)

m1 = V1/v1 = 0.005/6.201 = 0.00080632156 kg

P1 = 0.2501 (using the Steam Table)

Q12 = 0 (adiabatic; insulated)

However, I don't see how any of this is relevant to finding T2. Any help is much appreciated.

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