So last year, I was told by a friend that no Acceleration means no Force, Mathematically, this makes sense (500 Kg * 0 m/s^2 = 0 N), but intuitively, I can't wrap my head around it. Maybe this is because of language and the way we use the word force in normal conversation, but in physics it is also defined as a push or pull. So If I am pushing a box at a constant velocity (0 acceleration),does that mean I am not applying a force? Another thing that makes me believe that a force is applied is that I was told by my professor in lecture that (force is not actually Mass * Acceleration, but rather "It's What Happens".) Please help me wrap my head around this.