The ideal gas under study: treat one sealed body of gas as one parcel and enter its initial temperature and pressure. Two separated bodies (e.g. the two sides of a piston) need two parcels. The initial pressure can only be set on a parcel (containers and processes define no state variables): gas sealed by a cylinder, free gas, a tube closed at both ends, or a piston with friction or resting on a stop must have an initial pressure. Leave it blank where mechanics already fixes the pressure (a submerged bubble, a tube open to the atmosphere or dipping into a reservoir); over-specifying raises an “over-determined initial pressure” error.

Where the parcels sit: a cylinder (vessel) is one chamber; a glass tube (tube) is divided into gas columns, liquid columns, pistons and so on, ordered from top to bottom.

The changes the parcel undergoes in the order of the problem: heating, isothermal compression, pumping, rotating the tube… each process computes a new equilibrium state, and the p-V diagram draws the whole chain automatically.

All of the following are optional. Omitting them uses the engine defaults (g = 9.8, atmosphere 100000 Pa, SI units, 32 samples per process). You can skip this.