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.

Calculation

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.
Work done

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.
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1

Principles of Science I

1.1

Structure & Bonding

1.2

Properties of Substances

1.3

Cell Structure & Function

1.4

Cell Specialisation

1.5

Tissue Structure & Function

1.6

Working with Waves

1.7

Waves in Communication

2

Practical Scientific Procedures and Techniques

3

Science Investigation Skills

4

Principles of Science II

4.1

Extracting Elements

4.2

Relating Properties to use of Substances

4.3

Organic Chemistry

4.4

Energy Changes in Industry

4.5

The Circulatory System

4.6

Ventilation & Gas Exchange

4.7

Urinary System

4.8

Cell Transport

4.9

Thermal Physics

4.10

Materials

4.11

Fluids

5

Contemporary Issues in Science

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