Question

A particle starts from the origin goes along the x axis to the point (20,0) and then returns along the same line to the point (-20,0) Find the distance & displacement of the particle during the trip.

Answer 1

Displacement is the shortest distance between the final and the initial position of the particle with a sign i.e. negative or positive which depends on the sign convention adapted by you.
Distance is the total length of the path traveled by the particle.
so here, the shortest distance between the initial point i.e. origin and the final point i.e. (-20,0) is 20 but negative (sign convention) so the displacement is -20units.
Now, the distance traveled by the particle can be calculated as follows
the particle travels 20 units then returns back to the origin and then goes 20 units in the negative direction. so the length of the path=20+20 (to and fro) +20(in the negative direction)=60 units.
Thus, the distance covered by the particle is 60 units