Question

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?

Answer 1

Answer:

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