Let's go back to bare feet touching a cold floor, which was mentioned on the first page of this lesson. The animation you watched on that page described how cold objects have slower moving molecules and a lower thermal energy, or to put it another way, less heat. Now let's move on to the equally fantastic thought of your hand grabbing a spoon left in a cup of boiling tea. What's happening there? Well, molecules can move quickly too, and that's why the cup of tea, and the spoon left in it, are so hot.
So how did all those fast-moving molecules move from the boiling tea to the spoon? Watch this video to learn about how conduction transfers thermal energy between two objects. As you watch the animation, you might want to check the definitions of specific terms. In addition to the glossary words listed above, thermal equilibrium will be described. Stop the animation at any time, watch it again, or read the transcript.
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Touch a freshly brewed cup of tea and what do you feel? It is hot. But the cup didn’t start out that way. This is conduction in action.
Conduction is when atoms and molecules transfer energy between themselves by colliding. The hot water molecules collide with the molecules of the cup and in a few moments, that cup is too hot to handle. This is an example of energy transfer between two different “objects” that are touching--- the water and the cup. The molecules of the two substances stay in their particular place, but the energy is transferred between the two.
Energy can also move through objects. Put a room temperature spoon in that cup, and after a few minutes, the handle of the spoon will be hot. This is also conduction. The molecules within the spoon transfer thermal energy via collisions amongst themselves.
Conduction is how solid materials transfer thermal energy between themselves and through themselves to reach a balanced state called equilibrium.
And it’s just one of the main ways thermal energy moves through the things around us.
In the space below give two examples of energy transfer by conduction between two objects. Describe what happens to the motion of the molecules in both objects.