4.9.5

First Law of Thermodynamics

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The First Law of Thermodynamics

If we are interested in how heat transfer is converted into doing work, then the conservation of energy principle is important.

Illustrative background for Calculation Illustrative background for Calculation  ?? "content

Calculation

  • The equation for the first law of thermodynamics is:
    • The change in internal energy = the net heat transfer into the system - the net work done by the system.
    • ΔU=QW{\Delta}U=Q-W
  • Where U is the internal energy, Q is the heat and W is the work done by the gas.
Illustrative background for Work done Illustrative background for Work done  ?? "content

Work done

  • If the work is done by the gas the work done is positive, this is when a gas expands.
  • If the work done is on the gas the work done is negative, this is when a gas is compressed.
  • If the volume does not change there is no work done.

Jump to other topics

1Principles of Science I

1.1Structure & Bonding

1.2Properties of Substances

1.3Cell Structure & Function

1.4Cell Specialisation

1.5Tissue Structure & Function

1.6Working with Waves

1.7Waves in Communication

2Practical Scientific Procedures and Techniques

3Science Investigation Skills

4Principles of Science II

4.1Extracting Elements

4.2Relating Properties to use of Substances

4.3Organic Chemistry

4.4Energy Changes in Industry

4.5The Circulatory System

4.6Ventilation & Gas Exchange

4.7Urinary System

4.8Cell Transport

4.9Thermal Physics

4.10Materials

4.11Fluids

5Contemporary Issues in Science

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