A piston with stops containing water goes through an expansion process through the addition of heat. State 1 the pressure is 200 kPa and the volume is 2 m3. After half of the heat has been delivered the piston hits the stops corresponding to a volume of 5 m3. After all the heat has been delivered, state 2, the pressure is 1000 kPa with the piston resting on the stops. What is the work?

The work will be "600 kJ/kg".

Explanation:

(1-a) ⇒ Constant Pressure

(a-2) ⇒ Constant Volume

The given values are:

In state 1,

Pressure, P₁ = 200 kPa

Volume, V₁ = 2m³

In state 2,

Pressure, P₂ = 1000 kPa

Volume, V₁ = 5m³

Now,

In process (1-a), work will be:

⇒ W₁₋ₐ = P₁ (Vₐ - V₁)

On putting the values, we get

⇒ W₁₋ₐ = 200 (5-2)

⇒ = 200 (3)

⇒ = 600 kJ/kg

In process (a-2), work will be:

⇒ Wₐ₋₂ = 0

∴ (The change in the volume will be zero.)

So,

⇒ Total work = (W₁₋ₐ) + (Wₐ₋₂)

⇒ = 600 + 0

⇒ = 600 kJ/kg