activities will offer:
of the relationship between pressure and depth
opportunity to construct an experimental apparatus
in taking measurements with the apparatus
introduction to the impact of pressure on the lungs
1- DIVER IN A BOTTLE
two-liter plastic bottle with a cap
x 150 millimeter or smaller test tube (an eyedropper can
be used instead)
- Fill the bottle with water all the way to the top.
- Fill the test tube about halfway.
- Carefully and quickly turn the test tube over and push
it open-end first into the bottle, trapping an air bubble
in the top half of the tube. The tube should bob to the
surface. (An eyedropper may be substituted; in which case
it should not be inverted. The eyedropper should be inserted
about half-full of water.)
- Push the tube back into the bottle and fasten the cap.
Make sure there is no air space left under the cap.
- Squeeze the bottle and observe what happens to the diver.
- Record and analyze your observations.
In order for the diver to dive, it may be necessary to adjust
the size of the air bubble trapped in the test tube or eyedropper.
With the right air bubble size you should be able to control
the diver's depth very accurately, by varying the amount
of squeeze applied to the bottle -- even getting it to hover
at different depths.
- What happens to the diver as you squeeze the bottle?
- The lung capacity of the average adult is 5.5 liters
at the surface and only .37 liters at a depth of 100 meters.
- What happens to your diver's "lung" (a trapped air
bubble) as the diver descends in the bottle?
- Is this the same as squeezing the bottle with your
hands, or different?
2 - Three Streams from a Bottle
- Clear two-liter plastic bottle
- Nail or awl
- A ruler or measuring tape
- Large kitchen measuring cup, or graduated laboratory
- Clear tape, used to seal holes in the bottle. (If the
tape becomes too wet to stick, students can simply block
the holes with their fingers.)
- Duct tape
- A sink or large wash tub
- Graph paper
ONE- MEASURING STREAM LENGTH
with a partner.
- Punch three small holes in a vertical line down the
side of the bottle, one a few inches from the top, one
roughly in the middle, and close to the bottom. It is
important to make the holes as similar in size as possible.
- Measure and record the height of each hole above the
base of the bottle.
- Cover the holes with clear tape and fill the bottle
to the top with water. Do not replace the cap.
- Partner #1 positions the bottle inside the sink or wash
tub. When Partner #2 is ready, Partner #1 quickly removes
the tape from all three holes.
- Using three pieces of duct tape, Partner #2 quickly
marks the point on the sink bottom where each stream initially
- Measure and record the horizontal distance from each
piece of duct tape to the base of the bottle.
- How do the horizontal lengths of the streams compare
for the three holes?
- What is the relationship between stream length and hole
- What happens to the length of each stream as the water
level in the bottle decreases? Why?
- What is the effect, if any, of uncovering one or two
holes at a time, rather than all three?
TWO- MEASURING FLOW RATE
Rates of flow are found by collecting, in a measuring cup
or laboratory measure, the water flowing out of each hole
over a set time -- 20-30 seconds, for example, depending
on the size of the hole. The results can be expressed as
"fluid ounces per second" or "ml per second." It is important
that your measurements be made under similar conditions.
This means that the bottle should be refilled to the exact
same point between measurements.
- Cover the holes with new pieces of tape and refill the
bottle to the top.
- Partner #1 prepares to capture the top stream in the measuring
cup or laboratory measure, while Partner #2 prepares to
time with the stopwatch.
- Partner #1 removes the tape from the top hole and begins
collecting water, while Partner #2 simultaneously starts
the stopwatch. After 20 seconds, Partner #1 stops collecting
NOTE: you may need to adjust this time, depending on the
- Record your data.
- Repeat Steps #2-4 for the other two streams of water,
measuring each for the same amount of time as the top stream.
- How do the flow rates compare for the three holes?
- What is the relationship between flow rate and hole height?
- What might be the effect, if any, of measuring the flow
rate of each of the holes with the other two uncovered?
Try this out and compare your data.
- Within the deep ocean dwell animals that have developed
unique adaptations to the harsh environment of the deep
sea. Research how different species of marine life have
adapted to life at depth. (For more information, visit
our Video Database to watch "Hidden Depths" in SAF 405
"Creatures of the Deep")
- Conditions faced by the human body in the deep
sea are related both to those found in outer
space , and those found on high
altitude mountain peaks. Compare the conditions in
these three environments.
- Animal and human lungs work when the oxygen in the air
"diffuses" from the many tiny air sacs (alveoli) in the
lungs through membranes into the blood. The driving force
behind this diffusion is the pressure of the oxygen in
the lungs. At the same time, carbon dioxide diffuses out
of the blood into the lungs, from which it is then breathed
out. Explore the processes of breathing and respiration.
Research how fish gills function.
activity was contributed by Mark Moss. Mark has a Master of
Science in Environmental Studies and works as a consultant
in Southern California, developing environmental education
programs, curriculum, and supplemental materials for children
Advisors for this guide
Glickstein, Science Departmant, Waring School, Glouchester,
Corrine Lowen, Science Department, Wayland Public Schools,
Suzanne Panico, Science Department, Fenway High School, Boston,