1.Place a book on top of a table. What keeps the book from falling?
How is this possible?
2. Roll a marble on top of a level surface. Make it stop. Slide a light book
on top of the same level surface by giving it an initial push. Did the
book continue to slide? What is responsible for making the sliding
book slow down and eventually stop?
3. Drop a small stone and a piece of paper from the same height at the
same time. Observe closely the motion of the stone and the paper
as they fall. Which of them reached the ground first? Why did not the
other one reach the ground at the same time as the first?
4. What is the importance of friction in our daily life?
5. Why do we need gravity?