2. What two things do particles do when they are heated? 1. 2.

3. Because the particles speed up and get farther apart what happens to the volume of the object? 3.

4. Take a look at this side walk. Why is there a cut made in the cement? (hint: think of your last answer) 4.

5. Would the crack in the sidewalk be bigger or smaller in the summer? 5.

6. Look this bridge expansion joint. Here is an enlarged view. Why would bridges need these? 6.

7. Think of railroad tracks. They also have an expansion joint. How do you think this one works? 7.

8. What do you think might have happened to these tracks? 8.

9. Here is the answer to number eight. How did you do? This track was laid in February; the picture was taken in August.

10. Now for the really tough one. When you put a thermometer into hot water why does the mercury go up? 9.

11. How did you do?

12. Talk to your table partners and explain what is going on with this piece of metal. Brass side expands more than steel when heated, and contracts more when cooled.

13. Can you think of any other structures besides bridges and railroads that need to have expansion joints? List 3. 10. 11. 12.

14. Water is the only substance that does not contract with cold or the loss of heat.

15. Water molecules in crystal form have an open-structured hexagonal arrangement, so water expands upon freezing (water becomes less dense). Give an example of when you saw evidence of water expanding as it froze. 13.

16. Can you think of a reason that a pipeline would have to be like this? Why would it be made in segments? 14. 15.