The hammer brings the heat.

This lesson can show how friction holds a nail in wood, and the friction creates heat.

Materials:

• A typical hammer

• Large nails

• a piece of lumber, 2 x 4 or larger

• Don’t let any kids close to the hammer or wood . There are two nails, one driven into the wood and the other the student can hold. It usually feels cool or even cold. It feels ordinary. That’s case A.

• Keep students a distance from the wood and hammer where they can still see. Drive the nail into the wood more than halfway and quickly pull the nail back out. That’s case B, the driven nail.

Give the student the driven nail so that they have it in one hand and the unused nail in the other as in the picture at the top. The driven nail will feel hot because it has been forced into the wood which created friction, and the other feels cool, just the same as before.

What other ways can we create friction to warm something up?

Students reconvene for a class discussion of what we saw and felt. Write down the important parts they say and students can enter a short description of what we did and what we learned in their journals. Friction causes heat and our nail experiment has just shown us how.