Is a slow process always isothermal? Is a quick process always adiabatic?

An isothermal process is represented by the equation

PV = constant … (i),


P = pressure

V = volume.

To keep this product constant, a small change in V will only produce a small change in P and vice versa. Hence, an isothermal process is usually a slow process.

On the other hand, an adiabatic process is represented as