Second Law of Thermodynamics

Second Law of Thermodynamics

Heat cannot spontaneously flow from a colder body to a hotter body without external work.

### Entropy Form

$$\Delta S_{universe}\geq0$$

### Conditions / Special Cases

For reversible process:

$$\Delta S_{universe}=0$$

For irreversible process:

$$\Delta S_{universe}>0$$

### Usage

- Used to determine natural direction of processes.