Question
Sat April 04, 2015 By: Supriyo

Expert Reply
Yashvanti Jain
Mon April 06, 2015

Let the initial point of the farmer be point P

The distance covered by the farmer in 40 s is 4 × 10 = 40 m. 

The total time given: 2 min and 20 s = (2 × 60) + 20 = 140 s

Since the farmer moves 40 m in 40 s, therefore in 1 s the farmer covers a distance,
begin mathsize 12px style 40 over 40 straight m space equals space 1 space straight m end style

Therefore, the distance covered by the farmer in 140 s is:

140 × 1 m = 140 m.

Thus the number of rotations to cover 140 m along the boundary is:

begin mathsize 12px style Distance over Perimeter space equals space 140 over 40 space equals space 3.5 space rotations end style

So, the farmer will be at point R after 140 s.

So the displacement = PR = begin mathsize 12px style square root of 10 squared space plus space 10 squared end root end style = 14.1 m

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