# Problem: What is meant by the internal energy of a system?

###### FREE Expert Solution

Internal energy of a system:

$\mathbf{∆}\mathbf{E}\mathbf{=}\mathbf{q}\mathbf{+}\mathbf{w}$

For heat, q:

▪ + q → if the system gains, takes in, or absorbs heat or energy
▪ – q → if the system loses, evolves, gives off, or releases heat or energy

For work, w:

▪ + w → work is done on the system by the surroundings (volume: compresses)
▪ – w → work is done by the system on the surroundings (volume: expands)

###### Problem Details

What is meant by the internal energy of a system?