Q. A bind person after walking 10 steps in one direction each of length 80cm, turns randomly to the left or to right by 90$\circ$. After walking a total of 40 steps, the maximum displacement of the person from its starting point can be
A) Zero
B) $8\sqrt{2}m$
C) 16$\sqrt{2}$m
D) 32 m
Explanation
(c) This person cannot walk straight more than 10 steps.
Distance covered in 10 steps
$= 10 \times 0.8 = 8$m
As the person has to turn after every 10 steps, the only way to have maximum displacement is walk as shown in the figure.
[image:3_image200.emf]
The maximum displacement $= AE = AC + CE$
$= 8\sqrt{2} + 8\sqrt{2} = 16\sqrt{2}$m
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.