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```(Class – IX)
Page 100
An object has moved through a distance. Can it have zero displacement? If yes,
Yes, zero displacement is possible if an object has moved through a distance.
Suppose a body is moving in a circular path and starts moving from point A and
it returns back at same point A after completing one revolution, then the distance
will be equal to its circumference while displacement will be zero.
Question 2:
A farmer moves along the boundary of a square field of side 10 m in 40 s. What
will be the magnitude of displacement of the farmer at the end of 2 minutes 20
seconds from his initial position?
Given, side of the square field = 10 m
Therefore, perimeter = 10 m × 4 = 40 m
Farmer moves along the boundary in 40 s
Time = 2 minutes 20 s = 2 × 60 s + 20 s = 140 s
since, in 40 s farmer moves 40 m
Therefore, in 1s distance covered by farmer = 40 ÷ 40 = 1m.
Therefore, in 140s distance covered by farmer = 1 × 140 m = 140 m

Now, number of rotation to cover 140 along the boundary =

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(Class – IX)
= 140 m ÷ 40 m = 3.5 round
Thus after 3.5 round farmer will at point C (diagonally opposite to his initial
position) of the field.
Therefore, Displacement AC = √102 + 102 = √200 = 10√2 m
Thus, after 2 minute 20 second the displacement of farmer will be equal
to 10√2 m north east from initial position.
Question 3:
Which of the following is true for displacement?
(a) It cannot be zero.
(b) Its magnitude is greater than the distance travelled by the object.
None of (a) and (b) are true.