Thermodynamische systemen

In thermodynamics, the objects under observation are considered a system, and all the surrounding objects, outside the system's boundary,  are the environment.

A car, including the fuel inside its fuel tank, can be considered a system. The road along with the surrounding area is the environment.

If the car is stationary, it does not exchange any matter or energy with the environment. Such a system is called an isolated system.

When the car engine ignites, the fuel combustion lets out the exhaust gasses, the wheels experience the frictional force due to the road, moving the car forward. Here, both matter and energy are exchanged with the environment, and hence the car in motion can be considered an open system.

If the car's engine is turned off, the frictional force between the car wheels and the road gradually halts the car. Here, only energy, is exchanged between the system and the environment. Such a system is called a closed system.