Open the vacant drawer of the table. Put the pencil inside it as shown in the figure. Now place the pencil inside the drawer in such a way that you can see it. Close the drawer forcefully.
When the drawer is being closed, what is the direction of the pencil's motion? Why is this happening?
Important Questions on Time and Motion
Take a sheet of paper as large as your exercise book's page. Lay it on the table. Place a pencil box on it. Now pull the paper suddenly and forcefully. The pencil box does not move. It remains at the same place.
Think and say why did it happen so. Can you give an explanation using this law?
When we walk
When a fish swims in water.
I) Do you have to apply the same force in both cases against the pull of the earth(i.e. the weight of the bag)?
II) In which case you have to work more?
Case1: Put 10 books and 10 exercise books in your school bag. Now lift the bag from the floor onto the chair. Then lift it from the chair onto the almirah. Now answer the following questions.
Case2: Insert 10 books and 10 copies in the school bag. Lift it from the floor to the table. Now take out 10 copies and 5 books from the bag. Then put the bag down on the floor. Again, lift the bag onto the table. Now answer the following questions.
i) In which case do you have to apply more force against the weight of the bag?
ii) In which of the two cases have you done more work?
Take spring and pull it at both ends.
What is happening?
Does the spring move from one place to another? Or does it only change its shape?
Have you done any work?
What do you see? Is the hand pump displaced as a whole?
Why is the balloon inflated?
On which body is your force applied?
Has the force applied by you done any work?
Do you feel anything?
Does your chest expand or contract?
Who is applying the force for expansion or contraction of the chest and where?
Does the force do any work?
