Systems and the energy ledger

Interactive lesson
The system and the surroundingsInteractive lesson
Open, closed, or isolated?Interactive lesson
Heat is a transfer, not a substanceInteractive lesson
Heat or work?Interactive lesson
Two doors: heat and workInteractive lesson
The first law: the energy ledgerInteractive lesson
Balance the ledgerInteractive lesson
Find the missing flow

The direction of change

Interactive lesson
Keeps going, or needs driving?Interactive lesson
Spontaneous processesInteractive lesson
Heat's one-way streetInteractive lesson
Reversing the flow costs workInteractive lesson
What is spreading out?Interactive lesson
EntropyInteractive lesson
The second lawInteractive lesson
Why heat spreadsInteractive lesson
Will it happen on its own?Interactive lesson
No going backInteractive lesson
Why there's no going back

Engines and efficiency

Interactive lesson
Useful output, wasted outputInteractive lesson
Every engine sheds heatInteractive lesson
Why the heat must leaveInteractive lesson
Same input, different useful outputInteractive lesson
EfficiencyInteractive lesson
Always below 100%Interactive lesson
Calculating efficiencyInteractive lesson
Efficiency in reverseInteractive lesson
Reading a Sankey diagramInteractive lesson
Building a Sankey diagramInteractive lesson
The impossible machine