1. Thermal Energy and Heat
Expansion and Contraction
Wednesday, September 12, 2018Wednesday, September 12, 2018

2. Question – What would happen to the atoms in a piece of matter if we heated it?

3. When objects are heated, the particles gain energy, move faster, and need more space so the object expands – increases in volume “gets bigger”

4. When objects are cooled, the particles lose energy, move slower, and need less space so the object contracts – decreases in volume “gets smaller”

5. Experiments – It’s always better to try these yourself with your students, but depending on your supplies I’ve included videos
Ball and ring - video
balloon and Erlenmeyer flask - video
sagging wire

6. The amount objects expand and contract has been measured and calculated for a variety of materials.

7. Engineers must think about expansion and contraction before they build things because if they didn’t, their structures would be destroyed. e.g. bridges, railway ties, teeth fillings, etc.

8. Engineers must think about expansion and contraction before they build things because if they didn’t, their structures would be destroyed. e.g. bridges, railway ties, teeth fillings, etc.

9. Engineers must think about expansion and contraction before they build things because if they didn’t, their structures would be destroyed. e.g. bridges, railway ties, teeth fillings, etc.

10. Special case - water
Water is Weird !?
Chemically speaking, water is very weird. It doesn't behave at all like it should.
Ice shouldn’t float (but it’s lucky for us that it does)

11. Water is the only substance that expands as it freezes (it should contract!)

13. Homework question – In which season would you expect the telephone lines to sag the most? The least? Why? -