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The Potential and Kinetic Energy of Atoms
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The following ideas should now be familiar:
Kinetic energy is the energy of motion.
Potential energy is the energy of position.
How do these two energies relate?
If you skateboard upward, you slow down as you rise, which means that you lose kinetic energy. But because you gain height, you increase your potential energy. On the way down the skateboard track, the you speed up gaining KE, but losing PE. If you neglect friction, the total energy remains constant--the KE and PE change, but their sum remains the same. The same holds for an atom. As it loses PE, it gains KE in equal measure. As it looses KE, it gains the same amout of PE.
Use the following model to explore how KE and PE relate
The model below makes a graph of both the PE and KE of the red atom. Once again, the green atom is nailed down and the red atom has to move in the blue area.
Do this:
Before running the model, predict what the two curves (PE and KE) will look like.
Run the model.
Use the "tape" controls below the model to explore the relationship between the model and the graphs.
Red: Kinetic Energy, Blue: Potential Energy
The total energy is just the sum of KE and PE. What do you predict for the total energy for two atoms? The next page explores this question.
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<b><font size="5" face="Trebuchet MS">The Potential and Kinetic Energy of Atoms</font></b>
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<font face=Verdana size=4>Why does the KE increase as the red atom moves to the right?
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As the red atom moves to the right, there is an attractive force to the right. This increases the speed of the atom, which increases its KE.
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<font size="4" face="Verdana">Check the true statements below based on the
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Kinetic energy is always positive
Kinetic energy is always negative
Potential energy is always positive
Potential energy is always negative
The atom is at rest at D and E
The atom is at rest at B and G
There is almost no force at D and G
There is almost no force at D and E
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