question_answer

A particle is moving in a circular path of radius r. The displacement after half a circle would be    (NCERT Exemplar)

A) zero                                          

B) \[\pi r\]

C) 2r                                            

D) 2\[\pi r\]

Correct Answer: C

Solution :

[c] Given, after half the circle, the particle will reach the diametrically opposite point i.e., from point A to point B. And we know displacement is shortest path between initial and final point.

\[\therefore \] Displacement after half circle

= AB = AO + OB

\[=r+r=2r\ \ [\therefore \operatorname{Given},OA\ \operatorname{and}\ OB=r]\]

Hence, the displacement after half circle is 2r.