1What is friction? Explain how it is produced.
2What does the amount of friction depend on?
3A brick is dragged first on its large flat face and then standing on its narrow edge. Why is the force needed almost the same?
4Justify the statement that friction is both our enemy and our friend.
5Write any three measures of reducing friction, and explain how each one works.
6What is streamlining? Why is it done?
7Why is it harder to drag an object on a rough surface than on a smooth one?
8Explain why you would not be able to walk if there were no friction.
9Why does friction reduce the efficiency of a machine?
10Why is less force needed to roll an object than to drag it?