1-What is friction? Give 3 examples from Figure 5.8 2-What causes friction? How does the hockey puck on sandpaper help to explain?

3-Compare and contrast static and sliding friction. How does moving a refrigerator help you to
explain the difference?

4- What 3 factors can influence the amount of friction between two objects? Use Figure 5.10 to
help you explain.

5-What is the effect of putting oil in car engines? What would happen to the engine without the
oil?

6-Friction is not always a negative things. Identify 4 ways that friction is beneficial and useful.

7-Friction always produces .

8-True or False. It is possible to eliminate friction completely from moving parts.

9-Look at the picture of rocks on the bottom of page 122. Answer the question you observe in
between the two sets of rocks and explain your reasoning.

10-If the force squeezing two surfaces together is decreased, the force of dry sliding friction
between the two surfaces will most likely .
11-Suppose a mover is pushing a heavy box to the right across the tile floor. What two pieces of
advice could you give the mover about friction that would help the mover move the box more
easily?