Question

a farmer moves along the boundary of a square field of side 10m in 40 s .what will be the magnitude of displacement of the farmer at the end of 2 m 20 s from his initial position (write all the steps )

Answer 1

The Speed of Farmer is 40m/40s = 1 m/s

Distance travelled by the farmer in 2 min 20s or 140 sec = 1 x 140 = 140m

Suppose he started at edge of the field then he has completed 3 and a half rounds, so he is diagonally opposite of his initial position then,

Displacement = Length of Diagonal
= √2 x 10m
= 10√2 meters

Answer 2

Here, from the first case, we know his speed is 0.25 m/s. For the second case, (v=0.25 m/s, t=2 min 20s (i.e. 140 seconds). Thus, from formula (v=s/t), distance travelled is 35 metres in the given time frame.

Picture a square field in your brain. Wait..
Thus, the displacement is 5 metres.