Overview
Open the Experimental
Apparatus in a New Window
In this experimental module you will be working with particles inside
a balloon that is at constant volume (unless you pop it). You can control the temperature of the gas in the balloon by
grabbing the thermometer with the mouse and adjusting the temperature (in Kelvins)
up or down. Gauges read out the pressure (in weird units called Pascals) inside the
balloon as well as the MPS (mean particle speed measured in meters/sec). A graph shows the
distribution of particle speeds. The peak of that graph
is approximately the same as the mean particle speed (mps).
Experimental Procedure
Lab Notebook Link
 Make and record pressure and MPS measurements at temperatures of 100, 200,400,800 and 1600K
 The balloon material is only rated to 150 pressure units. Given your data at what temperature to you think the balloon will burst.
Test your prediction
 From your previous data, if you double the temperature does the MPS double? If not,
by what factor does it increase (i.e. 10%, 20%, etc ...).
 If you now increase the temperature by a factor of 4, by what
factor does the MPS increase?
 What do you think the proportional
relation is between Temperature and MPS?
 Now qualitatively describe how the graph, which is showing the
distribution of particle speeds, behaves as the temperature increases.
(ignore the red vertical line on the graph).
 Given this behavior, how would you physically state that temperature
manifests itself. That is, what does "temperature" really indicate?
 Clear the graphs and set the temperature to 400K to get one color curve
and then set the temperature to 1600 K to another curve. Count the approximate number of boxes
that are under the two curves. In doing this you are measuring
the amount of area under these curves (in calculus this is called an
integral). How many boxes are there for each temperature? (report them in the pressure column of the worksheet)
 Compare the two counts. Note that the Yaxis is the number of
particles per cubic centimeter that are at some velocity.
What might this comparison be telling you about the distribution of
particle energies in this enclosed volume?

Click to open a new balloon in a seperate window . Set the temperature
to 1200K. Record the MPS and pressure. Suggest a reason that the values
are different in this new ballon than in the previous one for this
temperature (e.g. the step 1 values)