The concept of equilibrium is a very important one to scientists
in all fields. Static equilibrium refers to a condition in which
the parts of a system have stopped moving, and is rare in nature.
Dynamic equilibrium refers to a condition in which the parts of
a system are in continuous motion, but they move in opposing directions
at equal rates so that the system as a whole does not change.
In this exercise, you will explore the concept of dynamic equilibrium.
Clear plastic containers (2), paper cups, water. meter stick.
Methods: Pour water into the plastic containers until the water level is the same in each container. Measure and record the depth of the water. Obtain two paper cups and submerge each in a separate container of water. When given a signal by one of the lab team members, simultaneously pour each cup of water into the other container. Repeat this process four more times, then measure and record the depth of the water. Then repeat the cycle of five transfers two more times, and measure the depth of the water after each cycle. Record your observations.
Pour all of the water into one of the
containers. Measure and record the depth of water in that container.
Proceed as before. At the beginning, one cup will be empty and
the other full. Simulate the pouring with the empty cup at each
transfer. As water is put into the empty container, gather as
much water as possible in the cup for each transfer. Measure and
record the depth of the water after each five transfers, and continue
until twenty transfers have been made. If time allows, do the
whole procedure again with different starting depths. Dispose
of the water and return the materials to the front desk.
Prepare a data table to record the
changes in the depth of the water in both containers under each
set of conditions. The table should have five columns: Time, Trial
1 Container 1, Trial 1 Container 2, Trial 2 Empty Container, Trial
2 Full Container. You may add more columns if you collect more
Prepare graphs of your data. Put time
on the horizontal axis and depth on the vertical axis. Be sure
to indicate the units of measure. Plot both the data for both
containers for each trail on the same graph (remember to use different
Science Education Connection|
Department of Biochemistry
The University of Arizona
Wednesday, February 12, 1997