The object starts moving from O which is the reference point. Class 9
The object starts moving from O which is the reference point. Class 9
Question 1.
The object starts moving from O which is the reference point (Fig.). Let A, B and C represent the position of the object at different instants. At first, the object moves through C and B and reaches A. Then it moves back along the same path and reaches C through B. Class 9
Answer:
- The total path length covered by the object is OA + AC = 60 km + 35 km = 95 km. This is the distance covered by the object
- For motion of the object from 0 to A, the distance covered is 60 km and the magnitude of displacement is also 60 km.
- During its motion from 0 to A and back to B, distance covered = 60 km + 25 km = 85 km while the magnitude of displacement = 35 km.
- If object moves back to 0, the final position coincides with the initial positionand therefore, the displacement is zero. However, the distance covered is OA + AO = 60 km + 60 km = 120 km.
Question 2.
Two persons A and B are moving towards each other from a distance of 210 km. Person A travels 9 km per day and B travels 5 km per day. They will meet each other in how many days and find the distance travelled by A and B. Class 9
Answer:
Two persons A and B have to travel distance of 210 km
Total distance travelled by person A and B in one day = 9 + 5 = 14 km
Time taken to travel distance of 210 km = 210/14 = 15 days
Person A will travel the distance in 15 days = 15 × 9 = 135 km
Person B will travel the distance in 15 days = 15 × 5 = 75 km