Question

when displacement become zero or negative​

Answer 1

the negative displacement means it has same magnitude but it's direction is opposite. Basically it depends upon the origin and reference. If we will take positive reference or direction toward a particular direction from origin then to represent its opposite direction we have to use the negative one.

Answer 2

Unlike distance, which can only get larger on any path taken, displacement can be positive, negative,or zero. Displacement is zero when you start and end at the same spot.

Thank you!

@itzshivani