I have arrived at the contradictory conclusion that a body can have a positive or negative velocity and not be moving(variating it's space). It is contradictory because if it has a positive or negative velocity it must be moving (variating it's space) since velocity is a variation in space, as physicians represent it mathematically:V=ΔS/Δt. There must be something wrong with my reasoning but I am unable to find what it is. Here is my reasoning: In physics there is the formula F=m.a(Force is equal to mass mutiplied by acceleration). If for example I press my hand against a wall, a physician would say that I am applying a force on the wall with my hand, so my hand's acceleration is different from 0, because if it were 0 the force would be 0. Since my hand is accelerating it's speed is changing since acceleration is change in speed. From that it follows that there are moments where the velocity of my hand is either positive or negative, and therefore is moving(variating it's space). But my hand is not moving at all.