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(Class – IX) Page 100 Question 1: www.tiwariacademy.com www.tiwariacademy.com An object has moved through a distance. Can it have zero displacement? If yes, support your answer with an example. Answer 1: 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. www.tiwariacademy.com 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? Answer 2: 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 = www.tiwariacademy.com A free web support in Education 1 (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. www.tiwariacademy.com 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. Answer 3: None of (a) and (b) are true. www.tiwariacademy.com www.tiwariacademy.com www.tiwariacademy.com www.tiwariacademy.com www.tiwariacademy.com www.tiwariacademy.com www.tiwariacademy.com A free web support in Education 2