Question

A boy runs on a circular track of radius 20 m and stops after covering one sixth of the track. The magnitude of his displacement will be

Answer 1

displacement of the boy will be 20.94 m

Answer 2

The answer is 20 m.

First of all, imagine the boy travelled the distance from A to B where A and B are points on the circumference of the circle, with centre O.

Now, in triangle AOB,

∠AOB = 60° ( It is one sixth of the angle of a circle)

OB = OA ( radii)

So, ∠OAB = ∠OBA-------------- eq 1.

In triangle AOB,

∠AOB+∠OBA+∠OAB = 180° ( Angle Sum Property)

So, ∠OBA=∠OAB=60° ( From eq 1.)

So, triangle AOB is equilateral

∴ AB = OA = OB= 20 m