Translations:Development/Tutorials/Physical Simulation/52/en

This might seem strange: if we just want to put the logic in here, no drawing, why would we need a QWidget? Answer, the logic includes the next time step, which is a so called slot. We discuss the slots later. Only this much here. Since we want to have a "slot" we require to inherit from QWidget, which has slots. This slot must be public, i.e. we want to access it from outside this class.