Benefit of Polymorphism [closed]

It is useful when you handle lists…
A short example:

List<CoolingMachines> coolingMachines = ... // a list of CoolingMachines 
for (CoolingMachine current : coolingMachines) {
    current.start();
}

Or when you want to allow a method to work with any subclass of CoolingMachines