In sound , we learn that the Newton got the speed of sound wrong because he assumed the travelling of a sound wave through the air to be isothermal, but Laplace said that the process was an adiabatic process , But how did he conclude that it was an adiabatic process?
This isnt about if sound waves or Isothermal or Adiabatic, its more towards they "why ?" part , if it is adiabatic then why ? what was the thought behind thinking it was adiabatic
The compressions and expansions involved in sound propagation happen at relatively high frequencies for mechanical processes. This means that these expansions and compressions are, in general, fast and short processes.
An isothermal compression or expansion of a gas needs to be carried out slowly, so that the gas cools or heats through the surroundings/heat bath as it compresses or expands. If you don't do this, the gas will heat up or cool, and then it will go back to the surrounding temperature - that's not isothermal.
Adiabatic processes in contrast tend to be quick, because you do not want to have heat exchange. Heat transfer requires time, therefore a very short process usually involves minimal heat transfer and it is usually adiabatic.
