UTF-8Brownian Motion: Discovering the Cause of Brownian Motionyellow_fabric.gifBrownian Motion: Discovering the Cause of Brownian Motion
Observing the Motion of Multiple Atoms
Observing just a couple of atoms:
Add 2 or 3 atoms to the container by clicking on the button above, then clicking inside the container. Then run the model.
Pause the model using the button above, and view the paths each of the atoms has taken. You can do this by clicking on the button above, and then clicking on an atom. If you click on that same atom, the path will be hidden again.
The motion of one of your atoms above is not quite the same as the Brownian Motion you observed on the first page. There are parts of an atom's path in your experiment where the atom travels straight for while. This was not seen by Brown. His particles continually changed direction, appearing to move randomly.
Simulating Brownian Motion:
Hightlight one of the atoms in your model by using the button above, and dragging the cursor over one of the atoms.
See if you can make this atom behave in a similar way as the particle Brown observed.
After answering the question above, click here to see a different view of Brown's experiment.
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<font face="Verdana, Arial, Helvetica, sans-serif" size="4">Click on one
of the buttons to the left to do the following:</font>
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<blockquote>
<br>
<img src="selectObject.gif">
 = click on an object to select and drag it<br><br><img src="dropPurpleAtom.gif"> =
add an atom by clicking on it and then clicking inside the model
container<br><br><img src="cutObject.gif"> = remove atoms by dragging
over them<br><br><img src="showTrajectory.gif"> = show and hide the path
an atom has travelled by clicking on it<br><br><img src="markObjects.gif"> =
drag over one or more atoms to highlight them<br>
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<font size="4"><strong>In the previous page you observed one single atom
moving. How is the movement of an individual atom different when there are
other atoms around?</strong></font>
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<font size="4"><strong>Another factor which affects Brownian motion is
temperature. Use the slider below the model to change the temperature. How
does temperature affect the motion of atoms and molecules?</strong></font>
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<font size="4"><strong>As you have seen, a single atom, alone, tends to be
very predictable. It doesn't change directions randomly. However, Brown
observed what appeared to him as random unpredictable movement. Why do you
think the particle he saw appeared to move in random directions?</strong></font>
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