Calculate the work (in kJ) when substance initially at 95 kPa, 19 m³ is expanded against a linear spring to 245 kPa, 67 m³.

Elements Of Electromagnetics
7th Edition
ISBN:9780190698614
Author:Sadiku, Matthew N. O.
Publisher:Sadiku, Matthew N. O.
ChapterMA: Math Assessment
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**Calculate the work (in kJ) when a substance initially at 95 kPa, 19 m³ is expanded against a linear spring to 245 kPa, 67 m³.**

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### Explanation

This problem involves a calculation of work done by a substance expanding against a linear spring. The work done during this process can be visualized in the context of mechanical work, often represented graphically via pressure-volume (P-V) diagrams.

#### Key Points:

- **Initial Conditions:** 
  - Pressure: 95 kPa
  - Volume: 19 m³

- **Final Conditions:**
  - Pressure: 245 kPa
  - Volume: 67 m³

In such cases, the linear relationship between pressure and volume during the process can be examined, where the work done is represented by the area under the curve in a P-V diagram.

### Methodology

To solve for the work done:
1. **Identify the type of process:** Linear spring expansion suggests a linear increase in pressure with volume.
2. **Calculate the work done:** The work is the integral of pressure with respect to volume, simplified to the area under the P-V curve for a linear spring.

#### Calculations of Work:
The work done \( W \) can be computed using the formula for the area under a straight line in a P-V graph:

\[
W = \frac{1}{2} (P_1 + P_2) \times (V_2 - V_1)
\]

Where:
- \( P_1 = 95 \text{ kPa} \)
- \( P_2 = 245 \text{ kPa} \)
- \( V_1 = 19 \text{ m}^3 \)
- \( V_2 = 67 \text{ m}^3 \)

This equation accounts for the triangular region under the linear curve from the initial to final state.

### Educational Perspective:

Understanding this concept requires comprehension of thermodynamic cycles and P-V diagrams, which are critical for visualizing work processes in mechanical systems. This scenario is a practical application of such principles, enhancing problem-solving skills in physics and engineering contexts.
Transcribed Image Text:**Calculate the work (in kJ) when a substance initially at 95 kPa, 19 m³ is expanded against a linear spring to 245 kPa, 67 m³.** --- ### Explanation This problem involves a calculation of work done by a substance expanding against a linear spring. The work done during this process can be visualized in the context of mechanical work, often represented graphically via pressure-volume (P-V) diagrams. #### Key Points: - **Initial Conditions:** - Pressure: 95 kPa - Volume: 19 m³ - **Final Conditions:** - Pressure: 245 kPa - Volume: 67 m³ In such cases, the linear relationship between pressure and volume during the process can be examined, where the work done is represented by the area under the curve in a P-V diagram. ### Methodology To solve for the work done: 1. **Identify the type of process:** Linear spring expansion suggests a linear increase in pressure with volume. 2. **Calculate the work done:** The work is the integral of pressure with respect to volume, simplified to the area under the P-V curve for a linear spring. #### Calculations of Work: The work done \( W \) can be computed using the formula for the area under a straight line in a P-V graph: \[ W = \frac{1}{2} (P_1 + P_2) \times (V_2 - V_1) \] Where: - \( P_1 = 95 \text{ kPa} \) - \( P_2 = 245 \text{ kPa} \) - \( V_1 = 19 \text{ m}^3 \) - \( V_2 = 67 \text{ m}^3 \) This equation accounts for the triangular region under the linear curve from the initial to final state. ### Educational Perspective: Understanding this concept requires comprehension of thermodynamic cycles and P-V diagrams, which are critical for visualizing work processes in mechanical systems. This scenario is a practical application of such principles, enhancing problem-solving skills in physics and engineering contexts.
Expert Solution
Step 1: Given data

Given:

Initial pressure (P1) = 95 kPa

Initial volume (V1) = 19 m3

Final pressure (P2) = 245 kPa

Final volume (V2) = 67 m3

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