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Consider a heat engine with a cycle described by the figure, with the volume and pressure at points A, B, C, and D given below.

Randomized Variables

VA = 0.75 × 10-3 m3

VB = 3.3 × 10-3 m3

PA = 2.85 × 106 N/m2

PB = 2.01 × 106 N/m2

PC = 0.45 × 106 N/m2

PD = 1.05 × 106 N/m2

Calculate the net work output, in joules, of the heat engine following path ABCDA.

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The net work output of the heat engine following path ABCDA is -2996 J. The negative sign signifies work done on the engine, characteristic of a heat engine cycle.

To calculate the net work output of the heat engine following the path ABCDA, you can use the formula for work done in a thermodynamic process:

Work = ∫(V₁ to V₂) P dV

The work done during each segment of the cycle (AB, BC, CD, and DA) will be the area under the corresponding segment on the P-V diagram.

Work done in segment AB (Isochoric process):

W_AB = P_A * (V_B - V_A)

Work done in segment BC (Isobaric process):

W_BC = P_B * (V_C - V_B)

Work done in segment CD (Isochoric process):

W_CD = P_C * (V_D - V_C)

Work done in segment DA (Isobaric process):

W_DA = P_D * (V_A - V_D)

The net work output is the sum of the work done in each segment:

W_net = W_AB + W_BC + W_CD + W_DA

Now, plug in the given values:

W_AB = (2.85 × 10^6 N/m²) * (3.3 × 10^(-3) m³ - 0.75 × 10^(-3) m³)

W_AB = 2.85 × 10^6 N/m² * 2.55 × 10^(-3) m³

W_AB = 7275 J

W_BC = (2.01 × 10^6 N/m²) * (0.45 × 10^(-3) m³ - 3.3 × 10^(-3) m³)

W_BC = 2.01 × 10^6 N/m² * (-2.85 × 10^(-3) m³)

W_BC = -5728.5 J

W_CD = (0.45 × 10^6 N/m²) * (0.75 × 10^(-3) m³ - 0.45 × 10^(-3) m³)

W_CD = 0.45 × 10^6 N/m² * 0.3 × 10^(-3) m³

W_CD = 135 J

W_DA = (1.05 × 10^6 N/m²) * (0.75 × 10^(-3) m³ - 3.3 × 10^(-3) m³)

W_DA = 1.05 × 10^6 N/m² * (-2.55 × 10^(-3) m³)

W_DA = -2677.5 J

Finally, calculate the net work:

W_net = W_AB + W_BC + W_CD + W_DA

W_net = 7275 J + (-5728.5 J) + 135 J + (-2677.5 J)

W_net = -2996 J

Therefore, the net work output of the heat engine following the path ABCDA is -2996 J. Note that the negative sign indicates that the net work is done on the engine, which is typical for a heat engine cycle.

User Stan Kurdziel
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