Living with Thermal Expansion and Contraction

Objective: Cite examples of how thermal expansion and contraction

affect everyday objects.

Number from 1-37, single lines.

Using the pictures of the world around us, name two ways that cause temperatures to change.1. Day to Night2. Seasons

List the three main states of matter:

3. Solid4. Liquid5. Gas

3. 4. 5.

6. Most matter _____ when heated. expands7. Most matter _____ when cooled. contractsThis is true for every state of matter.

8. _____ is the only substance that does not contract with cold or loss of heat.

water

9. Water molecules in crystal form have an open-structured hexagonal arrangement, so water _____ upon freezing. expands10. This makes it become less _____.dense11. Give an example of when you saw evidence of water expanding as it froze.

Expansion and Contraction of SolidsPeople who design structures such as buildings and bridges are very careful about the materials they use.

12. What would happen if they chose materials that would break when temperatures change?

A building project will often require two or more materials. Designers would not choose materials that expand and contract in different ways. 13. What would happen if one material expanded faster than another material?

• Think about solid materials you use or see every day.

• Write down these examples of solids that expand and contract.

14. Metal frames around windows

15. Hot-water pipes in homes

16.Car Engines

17. Metal lids on jars

18. What happens if your tooth and filling don’t contract and expand the same?

19. Do teeth expand and contract?Some scientists work on making new filling materials. They want these fillings to expand and contract just like real teeth.

Building with Concrete• Engineers use

steel rods to make concrete bridges and buildings stronger. The rods help support the concrete.

• 20. What happens if the steel doesn’t expand the same way as the concrete?

If the steel does not expand at the same rate as the concrete, the concrete can crack. Eventually the building could fall.

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

• Bridges and sidewalks are built in sections. There are spaces between the sections called expansion joints. Expansion joints allow steel and concrete to expand without cracking.

• 22. What are the cracks in the sidewalk for?

• 23. Would these cracks be bigger or smaller in the summer?

• Think of railroad tracks. They also have an expansion joint.

• 24. How do you think this one works?

This track was laid in February; the picture was taken in August 25. What do you think might have happened?

26. Can you think of a reason that a pipeline would have to look like this?

27. Why would it be made in segments?

Expansion and Contraction of Liquids

• Think about liquid materials you use or see every day.

• List examples of liquids that expand and contract:

28. Gasoline in cars

• Better to fill up in the morning. Gas is more dense in the cool morning.

• Never fill up when a truck is filling the tanks. The gas is less dense because it is full of bubbles.

29. Engine CoolantEngine coolant doesn’t freeze!

30. Oceans and Lakes

31. Alcohol in Thermometers

• In the last 100 years, the temperatures of oceans and lakes on Earth increased. Warmer oceans and lakes have a greater volume. When oceans have larger volumes, sea levels rise.

• 32. What effect might this have on the world?

Expansion and Contraction of Gases33. Gases that are heated will __________ in their containers. expand34. The energy of the gas particles will _______.Move faster The particles of warm gases hit the walls of the container more often. They also hit the walls harder.

• If the walls of the container are flexible, the walls expand. If the walls are not flexible and cannot expand, then the pressure inside the container increases.

• 35. Which of these two has flexible walls? A B

• Think about gases you use or see every day. • Write down these examples of gases

that expand and contract:

36. Air in tires

37. Air in a Soccer Ball

38. Air in Balloons

39. Air in an Air Mattress

40. What would happen if those materials did not expand and contract as they are meant to?

When cars and bicycles travel, their tires rub on the road. This makes the tires get hot. The air inside the tires will expand. If the tires are too full, they could burst.

Sports balls such as soccer balls are also filled with air.

41. What happens if you leave a soccer ball out in the cold?- the air inside the ball will contract. The ball will get soft and it will become unusable.

HOMEWORK• 1. Name two solid structures that expand and

contract.• 2. Name two liquids that expand and contract.• 3. What would happen to a bridge that did not

have expansion joints? Explain.• 4. Correct this statement to make it true: “The

particles in a material ‘get bigger’ when heated.”

• 5. Identify two examples of thermal expansion or contraction you have seen or used and explain how each affects you.