Changes around us
Chapter 6
Exercises (অনুশীলনী)
- To walk through a waterlogged area, you usually shorten the length of your dress by folding it. Can this change be reversed?
Ans:- We can reverse this change. We can bring the stranded water back to where it used to be.
- You accidentally dropped your favourite toy and broke it. This is a change you did not want. Can this change be reversed?
Ans:- This change is not a reversible change.
- Some changes are listed in the following table. For each change, write in the blank column, whether the change can be reversed or not.
- A drawing sheet changes when you draw a picture on it. Can you reverse this change?
Ans:- This change can be reversed. This is because a rubber can be erased and reversed.
- Give examples to explain the difference between changes that can or cannot be reversed.
Ans:- The difference between changes that can be reversible and cannot be counterproductive is- Things that have changed in the change that can be reversed can be brought back to their previous form.
For example, after preparing a boat with paper, the paper can be returned to its original form.
On the other hand, things that have been changed in the change that cannot be reversed cannot be returned to the previous form.
For example- after being caught in iron, it cannot be returned to the previous form. - A thick coating of a paste of Plaster of Paris (POP) is apploed over the bandage on a fractured bone. it becomes hard on drying to keep the fractured bone immobilised. Can The change in POP be reversed?
Ans:- The plaster of paris, which is coated on the bandage of broken bones, becomes harder to dry and keeps the fractured bone unable to move. This change in plaster of paris cannot be reversed.
- A bag of cement lying in the open gets wet due to rain during the night. The next day the sun shines brightly. Do you think the changes, which have occurred in the cement, could be reversed?
Ans:- Can’t, because even if the cement sack is dry well, the cement sack is no longer as good as before.