Question

a body is moving along a circular path of radius R. what will be the distance travelled and displacement of the body when it completes half revolution?

Answer 1

distance =2 pii r .
displacement =2r

Answer 2

distance travelled will be the half the circumference for one half revolution.. it is πr.
by definition distance is the total path covered.
it is a scalar quantity.
2----
whereas displacement is 2*r, because the final and intial state of body is same .
we know from definition of displacement that it change of body from final position to intial position.
displacement is vector quantity