Path length is always positive, while displacement can be positive, negative or zero first of explain this statement by a suitable example Why lenght is always positive
Answers
Yes. That is a very fundamental question your teacher answers you about in 11th std. physics. Displacement is a vector quantity which means it depends upon direction and magnitude. In other words, displacement could be defined as the shortest distance between two points. It can be possitive, zero or even negative.
On the other hand, distance covered by a particle in its journey is the total length of the path covered by the body from its starting point to the end point. Which means, as the particle starts its journey, distance can only increase throughout the journey. In case of displacement, it could increase, decrease or remain constant throughout the journey.
For example, when we throw a ball up in the air, for whole of the journey covered by the ball, displacement would be zero as the ball comes back to its original position in the final situation and hence the starting point and end point remains the same which means, shortest distance between terminal points=0 and hence displacement=0.
Whereas the distance covered by the ball during the journey would be twice the total height achieved by the ball. Which means distance≠0 in this case.
I hope you found your answer.