Experts please tell in detail : 

How is displacement helpful in science ? Why was it invented even though distance exists ?

Dear Student,
Displacement is the shortest distance between the final and initial position.It is a vector quantity.
Displacement =Final position-Initial position


Here we can see the difference in distance covered by a body and its displacement.
Distance can be defined as total length of the path travelled by the object.
For example red line indicates the distance.



Displacement may be defines as the difference between initial and final point of a distance travelled by the object.
For example



Differences between distance and displacement:
1.
• It is the length of the total path covered by the body.
• It is the shortest distance between the final and the initial point.
2.
• It only has magnitude, doesn’t have direction (scalar quantity).
• It has magnitude as well as direction (vector quantity).
3.
• Distance travelled is non zero whenever there is a linear motion.
• Displacement is zero if the body comes back to its initial position.
4.
• Distance measured is always positive.
• Displacement can be positive or negative depending on the reference point.
Regards