Q1.
Look around and prepare a list of five objects that are in motion and five objects that are at rest. Record your observations in Table 5.3. Think about how you decided whether an object was in motion or at rest. Write your explanation (justification) in Table 5.3.
Answer
Choose a reference point first — for a classroom activity, the school building or the ground is convenient — and then look at each object twice, a minute apart.
| Objects in motion | Justification | Objects at rest | Justification |
|---|---|---|---|
| Cow grazing in the field | It is at a different spot in the field a minute later | Tree | Its distance from the school wall never changes |
| Bus on the road | It has gone past the bus stop by the time we look again | Blackboard | It stays on the same wall at the same height |
| Blades of a running fan | A mark on one blade keeps returning to a new position each instant | School bench | It is at the same place in the room after a minute |
| Boy running in the playground | His distance from the goal post is decreasing | Electric pole | Its distance from the gate is always the same |
| Water flowing in a drain | A floating leaf is carried further along | Water in a bucket | The surface stays where it is |
How the decision was taken, in words: note where the object is with respect to the reference point, wait for some time, then look again. If it is now at a different distance or direction, it is in motion; if it is exactly where it was, it is at rest.
Why the reference point must be stated: the same object can appear on both lists. A passenger sitting in a moving bus is at rest with respect to the bus, but in motion with respect to a building on the roadside. Without naming the reference point, neither answer is right or wrong.
Try This: Write your five moving objects again, but this time choose the Sun as the reference point. Now even the tree and the electric pole are in motion, because the whole Earth is carrying them around the Sun.