Now look at what happens at the atomic level as the temperature of the cup goes down and the temperature of the counter goes up.

The model shows atoms from the cup and counter at the instant they touch. (Because atoms are so small, though, this model only shows a very small section of the cup and counter where they touch.)

Use the sun-shaped tool to heat the cup atoms. Pick up the sun-shaped tool and click it on the atoms from the cup (the green atoms). Heat them to about 60 degrees. (You can check the current temperature on the graph.)

The yellow arrow on each atom shows the speed and direction of that atom. (The speed of the atom is its kinetic energy.)

When you have heated the atoms to about 60 degrees, press the Run button to start the simulation.

When the simulation starts, what can you say about the speeds of the cup (green) atoms in comparison to the speeds of the counter (blue) atoms? How do they compare in the end? What is happening to the atoms of the cup as the temperature of the cup cools down? What is happening to the atoms of the counter as the temperature of the counter rises?

What do you think will happen if the cup atoms start at a higher temperature? Try it!

If you want, you can also put a check in the box below to make the atoms with high kinetic energy red and atoms with low kinetic energy white.