Thermodynamics
First Law of Thermodynamics
Energy conservation: ΔU = Q - W (physics convention).
Variables
ΔUJ
Internal energy change
Change in internal energy
QJ
Heat added
Heat into system
WJ
Work done
Work by system
Derivation
Fundamental law of energy conservation.
Your notes
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Common questions
What is the First Law of Thermodynamics formula?
First Law of Thermodynamics is written ΔU = Q - W. Energy conservation: ΔU = Q - W (physics convention). It belongs to Thermodynamics, under First Law.
What are the units in ΔU = Q - W?
In SI units, ΔU is internal energy change, measured in kg·m²/s²; Q is heat added, measured in kg·m²/s²; W is work done, measured in kg·m²/s².
How is the First Law of Thermodynamics formula derived?
Fundamental law of energy conservation. The result is ΔU = Q - W.