Archimedes’ Principle
012-10998 r1.04
Archimedes’ Principle
Introduction
Journals and Snapshots
The Snapshot button is used to capture the
screen.
The Journal is where snapshots are stored
and viewed.
The Share button is used to export
or print your journal to turn in your
work.
Each page of this lab that
contains the symbol
should be inserted into your
journal. After completing a
lab page with the snapshot
symbol, tap
(in the upper
right corner) to insert the
page into your journal.
Note: You may want to take a
snapshot of the first page of
this lab as a cover page for
your journal.
Archimedes’ Principle
Lab Challenge
What force causes some things
to float while others sink?
Archimedes’ Principle
Background
Archimedes (287 to 211 B.C.) lived in
the Greek colony of Syracuse on the
island of Sicily, and is considered to be
one of the greatest mathematicians of all
time. Although there are many images of
Archimedes, no true likeness has
survived. One of his discoveries, that has
lived on, is that an object submerged in
a fluid displaces a volume of the fluid
that is equal to the volume of the object.
Archimedes’ Principle
...Background
Following in Archimedes footsteps, we will observe
what happens to objects that are submerged and try
to determine the difference between objects that
float and those that sink.
Archimedes’ Principle
Materials and Equipment
Collect all of these materials
before beginning the lab.
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Force Sensor
Overflow Can
2 Small Cups
String
Rod Stand
Right Angle Clamp
Short Rod
Object to submerge
Water
Ruler
Balance (1 per class)
Note: Graduated cylinder not used in this lab.
Archimedes’ Principle
Sequencing Challenge
A. Calculate the
force due to gravity
on the volume of
displaced water
(weight in N).
B. Completely
submerge an object
in water, collecting
the volume of water
displaced by the
object.
C. Show that the
change in net force
on the object before
and after
submersion is equal
to the weight of
displaced water.
D. Measure the net
force(s) acting on an
object.
Hint: This step is
used twice
The steps to the left are part
of the procedure for this lab
activity. They are not in the
right order. Determine the
correct sequence of the
steps, then take a snapshot
of this page.
Archimedes’ Principle
Setup
1. Attach the Force Sensor to the rod stand
using a short rod and the right angle clamp.
2. Connect the Force Sensor to your SPARK
Science Learning System.
3. Press the zero button on the Force Sensor.
4. Place the overflow can below the force
sensor.
5. Tie a loop of string to the object, long
enough to allow the object to be submerged
completely in the overflow can when hung
and lowered from the force sensor.
Archimedes’ Principle
Setup
6. Place a dry cup (catch basin) under the spout
of the overflow can.
7. Fill the Overflow Can with water to the limit.
Note: To reach the fill limit of the can, overfill the
can allowing the excess water to pour from the
spout. When the spout has stopped dripping, the
can will be completely filled. Be sure to empty the
catch basin after doing this.
Archimedes’ Principle
Setup
Q1: Why is it important to fill the water to the point
that begins to run out of the spout of the
Overflow Can?
a) to ensure we capture all the water that is
displaced by the mass
b) to make sure we maximize the dilution
c) to insure that we minimize the amount of water
that is captured
d) to eliminate the need to refill the can
Make your selection below
then take a snapshot of this
page.
Archimedes’ Principle
Collect Data
1. Use a balance to measure
the mass of the empty
cup (catch basin) in kg.
2. Record the cup's mass in
the table to the left.
*To Enter Data into a Table:
1. Tap
to open the tool
palette.
2. Tap
then tap a cell in
the data table to
highlight it in yellow.
3. Tap
to open the
Keyboard screen.
Archimedes’ Principle
Collect Data
3. Measure the mass of the
object you will submerge
in the water, in kg.
4. Record the object's mass in
the table to the left.
*To Enter Data into a Table:
1. Tap
to open the tool
palette.
2. Tap
then tap a cell in
the data table to
highlight it in yellow.
3. Tap
to open the
Keyboard screen.
Archimedes’ Principle
Collect Data
5. Measure the dimensions of
the object then calculate its
volume.
6. Record the object's volume
in the table to the left.
*To Enter Data into a Table:
1. Tap
to open the tool
palette.
2. Tap
then tap a cell in
the data table to
highlight it in yellow.
3. Tap
to open the
Keyboard screen.
Archimedes’ Principle
Collect Data
Q2: Why is it important to measure the mass of the
empty cup?
a) to be sure the cup is not too heavy for
the experiment
b) to make sure the cups are of equal mass
c) to calculate the cup's body mass index
d) to ensure we can get an accurate measure of
the amount of water displaced by the hanging
mass
Make your selection below
then take a snapshot of this
page.
Archimedes’ Principle
Collect Data
7. Use the string loop to hang the object from the force sensor hook. Make
certain that the object is not swinging before recoding data.
8. With the object not yet submerged, tap
9. Tap
to begin recording data.
to record the initial net force acting on the object.
Archimedes’ Principle
Collect Data
10.Loosen the thumbscrew mounted to the crossbar
and rod stand and slowly lower the object into the
overflow can. Displaced water from the overflow
can should pour into the empty cup (catch basin).
11.Tighten the thumbscrew holding the object fully
submerged, but not touching the bottom of the can.
Note: If water fails to pour from the spout when the object is
submerged you may need to clear the spout on the overflow
can. Water will sometimes form a seal across the spout
opening with enough surface tension to prevent any
overflow. To clear it, first remove the object from the water,
then blow softly down the spout of the overflow can clearing
the passage.
Archimedes’ Principle
Collect Data
12.With the object fully submerged, tap
force acting on the object.
13.Tap
to stop data collection.
a second time to record the new net
Archimedes’ Principle
Collect Data
14.Use a balance to Measure
the mass of the cup (catch
basin) and water that has
overflowed from the can.
15.Record that mass in the
table to the left.
*To Enter Data into a Table:
1. Tap
to open the tool
palette.
2. Tap
then tap a cell in
the data table to
highlight it in yellow.
3. Tap
to open the
Keyboard screen.
Archimedes’ Principle
Analysis
If the mass of the object does not change
when it is submerged, but the net force does,
we must be observing the action of a second
force on the object. This force is called the
Buoyant Force. The force on the submerged
object is the resultant of the vector addition
of the force of gravity and the buoyant force
Mg
acting on the object.
Resultant
Buoyant
Force
Archimedes’ Principle
Analysis
The two tables on the next page (page 21) will be used to answer the Analysis
questions on pages 22 and 23. Please refer back to these tables for any of the
measured quantities in this lab.
Archimedes’ Principle
Archimedes’ Principle
Analysis
1. Calculate the mass of the
2. In the text box below,
3.
displaced water in kg by
calculate the weight of the
subtracting the mass of the
displaced water in newtons
empty cup from the mass of by multiplying the mass of
the displaced water and cup the water by the acceleration
together.
of gravity (9.81 m/s2).
In the text box below,
calculate the buoyant force
by subtracting the force
submerged from the force
due to gravity.
Archimedes’ Principle
Analysis
4. In the text box below,
compare the mass of the
object to the mass of the
displaced water.
5. In the text box below,
6. In the text box below,
compare the volume of the
compare the buoyant
object to the mass of the
force to the weight of
water displaced.
the water displaced,
then take a snapshot
of this page.
Archimedes’ Principle
Synthesis
1. What would a submerged object do if the buoyancy force were greater than the
force of gravity on the object?
Archimedes’ Principle
Synthesis
2. Imagine a person in a deep pool. What happens to the person if they:
a) let the air out of their lungs? Why?
b) take a deep breath and hold it? Why?
Archimedes’ Principle
Multiple Choice Question
1. A completely submerged object displaces its own
_________________.
a) density of fluid
b) weight of object
c) volume
d) mass
Make your selection below
then take a snapshot of this
page.
Archimedes’ Principle
Multiple Choice Question
2. What is the buoyant force acting on a 20-ton ship
floating in the ocean?
a) 20 tons
b) less than 20 tons
c) more than 20 tons
d) depends on the density of seawater
Make your selection below
then take a snapshot of this
page.
Archimedes’ Principle
Multiple Choice Question
3. A lobster crawls onto a bathroom scale
submerged at the bottom of the ocean.
Compared to its weight above the surface,
the lobster will have an apparent weight
under water that is ________________.
a) less
b) the same
c) more
d) depends on the density of seawater
Make your selection below
then take a snapshot of this
page.
Archimedes’ Principle
Congratulations!
You have completed the lab.
Please remember to follow your teacher's instructions for cleaning-up and submitting
your lab.
Archimedes’ Principle
References
ALL IMAGES WERE TAKEN FROM PASCO DOCUMENTATION, PUBLIC DOMAIN CLIP ART, OR WIKIMEDIA
FOUNDATION COMMONS:
http://commons.wikimedia.org/wiki/File:ALVIN_submersible.jpg
http://commons.wikimedia.org/wiki/File:Auftrieb_Archimedes_1.svg
http://commons.wikimedia.org/wiki/File:041108-N-0780F-066.jpg
http://commons.wikimedia.org/wiki/File:Canada_Goose_Lake_Union.JPG
http://www.freeclipartnow.com/office/paper-shredder.jpg.html