Hello, Inside a theoretical perfectly isolated system, momentum and energy are conserved. But is it possible to imagine a system gaining/losing energy while its momentum remains the same, or a system gaining/losing momentum while its energy remains the same? Or does one necessarily imply the other? The way I see it, if the system consists of one macroscopic body, then its momentum is equal to the vectorial sum of the momentums of all its atoms. So if this body was to gain energy in the form of heat, then its atoms would vibrate more rigorously, thus if on average all these atoms "pushed" equally more in all directions then wouldn't this body be an example of a system gaining energy while keeping the same momentum?