Question

Example of adiabatic process in real life

Answer 1

There's a story that Newton tried to calculate the speed of sound after making some simple assumption about air, but he essentially assumed the process was isothermal, and got the wrong answer. Assume it's adiabatic and you get an excellent estimate of the speed of sound.

Physicists also use "adiabatic" in a more general context than classical thermodynamics.  It refers to a process in which the energy levels of a system change slowly compared to the system's characteristic relaxation time.  For example, a waiter walking up a flight of stairs wants to deliver drinks adiabatically.  Although the potential energy of the cup of water must rise and so the waiter must deliver energy into the cup, he doesn't want any of that energy to excite the sloshing or twirling motions of the water.  If you successfully carry a cup of water full to the brim up a flight of stairs without spilling, you've done it adiabatically.

Similarly, if you have an atom in some particular quantum state and you turn on an electric field, the energy of the state will change.  If you turn on the electric field quickly, the atom will go into a superposition of several quantum states.  If you do it slowly, you'll find that the atom is still in the same state it was, just with a new baseline energy.  This sort of slow process is called "adiabatic".