We know that a null vector (or zero vector) has direction but no magnitude. I am having some trouble understanding this concept. 1. What's the direction of a null vector, really? 2. Also as null vector is a vector, can velocity or acceleration also be null vectors? 3. If so, then what does a null velocity vector mean? Under which physical condition a particle can have such velocity? 4. Similarly, what does a null acceleration vector mean? Is there any physical example? I guess the example of a null position vector would be the position vector of a particle which is at the origin of the coordinate. Is this correct? I don't know if these have been asked before (couldn't find using the forum search). I appreciate your help. Thanks in advance.