Question

The distance and displacement covered respectively by a particle after half a revolution of the circular path of radius $r$ are

• A. $\pi r,r$
• B. $2\pi r,2r$
• C. $2r,\pi r$
• D. $\pi r,2r$

Answer 1

The correct option is D $\pi r,2r$

Let a particle starts from point $A$ and reaches to point $B$ of a circular path of radius $r$ as shown in the figure.


So, distance is the total path length covered, which is arc length $AB$, thus, distance is
$\frac{2\pi r}{2}=\pi r$
And the displacement will be the length $AB$ i.e diameter of the circular path. Hence, displacement is $2r$