What happens to solids as they are heated and cooled?

What happens to solids as they are heated and cooled?

Materials needed

• ·         Wire, about  1 m (1 yd.) long
•               Large nail or small bolt

• ·            Candle

• ·             Match

Procedure

1.   Wrap one end of the wire around the nail and anchor the other end to a support. Adjust the wire so the nail swings freely but barely missies the table or floor.

      2.       Light the candle and heat the wire. 
      3.       Observe the nail. What happened?
      4.       Remove the candle and allow the wire to cool.          
      5.   Observe the nail. What happened?

6.       What can you say about the effect of heat on solids?

For problems solvers: 

did you ever notice how hard it is to remove the ring from a jar of fruit? Try running hot water over the lid, and then remove it. What do you think makes the difference?

Why are sidewalks made with joints every few feet? See what you can learn about expansion joints. See if you can find expansion joints as you drive across over passes or bridges on the highway. Why are these joints built into the bridge? Try to find expansion joints in large buildings.

If you know an automobile mechanic, ask him or her why wheel bearings are sometimes installed on axles when they are very hot.