Energy Transfer 1

What type of energy transfer occurs when you touch an object?  Conduction

When you touch something, you warm it up. What happens to the energy after you take your hand away? Does it go somewhere or stay in place?

**REMEMBER**  Before you start, warm up your hands since our room is sooooo cold  Before you start, warm up your hands since our room is sooooo cold  Use various materials: desk top, paper, notebook. Warm your hands; place your hands on these items. Then put the sensing sheet on top of the area you warmed and observe its response.

Foam: What does the temperature pattern tell you: where did the energy from your hand go and where did it not go? TTTThermal energy went from hand to foam, and then to the sensing sheet. The warmed area of foam stayed in the shape of a hand. That means energy did not go from the warm part of the foam to the cooler parts.

Aluminum and Foam: Where did the thermal energy go?  The pattern is much less defined. Energy went to the aluminum and did not stay in the shape of a hand. It went to parts of the aluminum that were not touched.  With the aluminum on the foam, the thermal energy stays in it, and after a while the temperature sensing sheet may show a nearly uniform color.  The foam must be under the aluminum. It keeps the energy from your hand contained mostly to the aluminum, but preventing it from flowing on to the desk top.

Where does the thermal energy go when you touch part of a metal disk?  Then energy has spread through the metal.

Plastic Disk: Where does the thermal energy go this time? IIIIt stays on the side of the disk where we put it; the rest of the disk does not warm up.

Is the plastic disk a conductor or insulator?  The plastic disk must be an insulator. Thermal energy given to one area of the disk stayed in that area, it did not move throughout the disk like it did with the metal conductor.