JSSS Round 2
Teacher Support Material
To investigate the relationship between pressure and depth
for a liquid
OP11
Introduction
The approach being used here is one of guided discovery. It is designed to maximise students’
involvement in their own learning. In this investigation, Students find out for themselves through
experiment about the effect of depth in a liquid on pressure.
Note
While datalogging is used in this investigation there are other, equally valid, techniques for
investigating the relationship between pressure and depth. There are also a variety of datalogging
systems available which are suitable for this investigation
Prior knowledge
From OP10, students should have an understanding of the concept of pressure.
Practical investigations
Students should be given the equipment, and allowed to work their way through one of the
worksheets. The gas pressure sensor can be used either simply as a meter or as a datalogger
which can produce a graph of depth vs. pressure. Essentially the choice is for the teacher.
In many cases, students will have used other ways of investigating the effect of depth on pressure
in a liquid. The activity described below could be carried out as a teacher demonstration to verify
their results
1.
Using a gas pressure sensor as a meter
The investigation is carried out as in the student material.
Extension 1
Repeat the investigation using methylated spirits and compare the results with those obtained for
water.
Extension 2
An investigation could be carried out to examine the variation of pressure with height.
If the height of a local hill/mountain is known, finding the pressure at the top of the
hill/mountain using the pressure sensor would allow a relationship to be established between
height and pressure. This would then allow the heights of other mountains/hills to be determined
from measurements of the pressure.
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JSSS Round 2
Teacher Support Material
Alternatively, if the relationship between height and pressure change is known, the height of a
mountain/hill could be found.
This is the principle of operation of an altimeter in an aeroplane.
Sample data can be found on the JSSS website.
2.
Using a gas pressure sensor to produce a graph
The investigation is carried out as described in the student material. Students can be guided to
deduce information from the graph.
To examine the graph
With the graph on the screen:
•
Press ENTER
•
Select ANALYZE by pressing 4
•
Select CURVE FIT by pressing 2
•
Select LINEAR (CH1 VS ENTRY) by pressing 1
The screen now shows the equation of the line: Y = A* X + B
Note the slope A _______________________________________________________________
What does the intercept B represent? _______________________________________________
•
Press ENTER to see the best fit line for the data.
To repeat the process or exit out of the program
•
Press ENTER
•
Select RETURN TO MAIN SCREEN by pressing 1
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JSSS Round 2
Teacher Support Material
Extension 1
The investigation using the datalogger to draw the graph may be repeated with different liquids
to show that the pressure depends on the density of the liquid. The line will have a different slope
for liquids of different density. The relationship between the slopes (obtained from the equation
of the line) and the densities of the liquids could be investigated.
The data could also be viewed on the calculator (see note below). Direct comparisons could be
made between the pressure in water and the pressure in methylated spirits at known depths. The
students could be presented with the following exercise.
What was the pressure at a depth of 20 cm in water?
_____________________________________________________________________________
What was the pressure at a depth of 20 cm in methylated spirits?
_____________________________________________________________________________
What is the reason for the difference between the two readings?
_____________________________________________________________________________
Is there a difference between the pressure in the water and the pressure in the methylated spirits
at all depths? __________________________________________________________________
_____________________________________________________________________________
Can you see any pattern in the differences?
_____________________________________________________________________________
Viewing data on the calculator
The table of the data obtained can be examined by carrying out the following steps
•
Press STAT on 2nd row.
•
Select Edit by pressing 1.
•
The lists of data now appear on the screen as a table.
The graph can now be manually plotted.
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JSSS Round 2
Teacher Support Material
Student Feedback
Whether the graph is plotted manually by the students or produced by computer, the following
exercise could be given.
1. What is the relationship between pressure and depth in a liquid? _______________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
2. Using your graph, estimate the pressure when the depth is 0 cm. _______________________
What is this pressure called? ______________________________________________________
_____________________________________________________________________________
3. Could this pressure have been measured in any other way? ____________________________
_____________________________________________________________________________
4. Try out your idea and write down your result. ______________________________________
_____________________________________________________________________________
5. Use your graph to estimate the pressure at a depth of 1 m in water.______________________
_____________________________________________________________________________
6. How much greater is the pressure at 1 m compared with the pressure at the surface of the
water?
_____________________________________________________________________________
7. Can you now predict what the pressure would be at a depth of 2 m in water? ______________
_____________________________________________________________________________
8. What would the pressure be at a depth of 10 m in water? _____________________________
_____________________________________________________________________________
The students could now look at the implications of this for divers, etc.
There is more information and data re diving on the JSSS website.
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JSSS Round 2
To investigate the relationship between pressure and
depth for a liquid (Logger and Computer)
OP11
Apparatus
Logger, calculator, gas pressure sensor, long thistle funnel, piece of rubber tubing and
graduated cylinder
Computer logger
Computer
Gas pressure
sensor
Thistle funnel
0
10
20
30
40
Graduated
cylinder
Procedure
1. Connect the end of the thistle funnel to the pressure sensor using the piece of
rubber tubing.
2. Mark 10 cm intervals along the side of a 1000 cm3 graduated cylinder as
shown and fill with water to the 0 cm mark.
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JSSS Round 2
3. Attach the Gas Pressure Sensor to CH1 of the computer logger. Attach the
logger to the computer.
4. Start the computer logger program.
5. A screen appears with three windows.
6. Maximise the Read Meter window on the top right of the screen - we now
have a pressure meter.
7. Lower the thistle funnel into the water and read the pressure at depths of 10,
20, 30, 40 cm etc., Complete the table.
Depth / cm
Pressure / kPa
10
20
30
Plot a graph of pressure against depth.
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JSSS Round 2
To investigate the relationship between pressure and depth for a
liquid using a datalogger to draw a graph
OP11
Apparatus
Logger, calculator, gas pressure sensor, long thistle funnel, piece of rubber tubing and graduated
cylinder
Gas pressure sensor
T
Thistle funnel
0
Calculator
10
Logger
20
30
40
Graduated
cylinder
.
Procedure
1. Connect the end of the thistle funnel to the pressure sensor using the piece of rubber tubing.
2. Mark 10 cm intervals along the side of a 1000 cm3 graduated cylinder as shown, and fill with
water to the 0 cm mark.
3. Attach the gas pressure sensor to CH1 of the logger. Attach the logger to the calculator.
4. Press the APPS button on the 3rd row of the calculator.
5. Start by pressing the number which is in front of DataMate on the screen.
6. Press the CLEAR button and wait for the screen to settle.
7. Select SETUP from the main screen by pressing 1.
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JSSS Round 2
8. Using the blue cursor key
on the right, move the black arrow on the screen down to MODE
and press ENTER.
9. Select EVENTS WITH ENTRY from the SELECT MODE menu by pressing 3.
10. Select OK by pressing 1.
Procedure to obtain data
1. Hold the thistle funnel with its base under the water at the 10 cm mark on the graduated
cylinder.
2. Select the START by pressing 2.
3. Press ENTER.
4. Insert 10 as the value for depth and press ENTER.
5. Lower the thistle funnel so that its base is at the 20 cm mark.
6. Press ENTER.
7. Insert 20 as the value for the depth and press ENTER.
8. Continue the process for each graduation mark.
9. Press STO (on the left on the 2nd row from bottom) to finish. A set of points appear on the
screen.
To examine the graph
•
Press ENTER.
•
Select ANALYZE by pressing 4.
•
Select CURVE FIT by pressing 2.
•
Select LINEAR (CH1 VS ENTRY) by pressing 1.
The screen now shows the equation of the line: Y = A*X + B.
Note the slope A. ______________________________________________________________
What does the intercept B represent? _______________________________________________
•
Press ENTER to see the best fit line for the data.
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JSSS Round 2
To repeat the process
•
Press ENTER
•
Select RETURN TO MAIN SCREEN by pressing 1.
The experiment can now be repeated.
Conclusion
What is the relationship between pressure and depth in a liquid?
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
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JSSS Round 2
To investigate the relationship between pressure and
depth for a liquid using a Logger as a meter
OP11
Apparatus
Logger, calculator, gas pressure sensor, long thistle funnel, piece of rubber tubing and
graduated cylinder
Gas pressure sensor
T
Thistle funnel
Calculator
0
Logger
10
20
30
40
Graduated
cylinder
Procedure
1. Connect the end of the thistle funnel to the pressure sensor using the piece of
rubber tubing.
2. Mark 10 cm intervals along the side of a 1000 cm3 graduated cylinder as
shown. Fill with water to the 0 cm mark.
3. Attach the pressure sensor to CH1 of the logger. Attach the logger to the
calculator and turn the calculator on.
4. Press the APPS button on the 3rd row of the calculator.
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JSSS Round 2
5. Start the DataMate program by pressing the number which is in front of
DataMate on the screen.
6. Press the CLEAR button and wait for the screen to settle.
7. The value of the pressure can be read on the top right of the calculator screen.
Investigation
1. Hold the thistle funnel with its base under the water at the 10 cm mark on the
graduated cylinder. Read the pressure from the calculator screen.
2. Repeat this at 20 cm, 30 cm, etc., and fill in the table below.
Depth / cm
Pressure / kPa
10
20
30
Draw a graph of pressure against depth.
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JSSS Round 2
Student
To investigate the relationship between pressure and depth
for a liquid using a datalogger to draw a graph
OP11
Introduction
This investigation will examine pressure readings on a sensor when placed in a funnel of water at
different depths. Readings like this are taken by divers when surfacing from dives to allow body
metabolisms to adjust to gases used when diving.
Apparatus
Logger, calculator, gas pressure sensor, long thistle funnel, piece of rubber tubing and graduated
cylinder
Gas pressure sensor
T
Thistle funnel
0
Calculator
10
Logger
20
30
40
Graduated
cylinder
Procedure
1. Connect the end of the thistle funnel to the pressure sensor using the piece of rubber
tubing.
2. Mark 10 cm intervals along the side of a 1000 cm3 graduated cylinder with the zero mark
near the top as shown. Fill with water to the 0 cm mark.
3. Attach the gas pressure sensor to CH1 of the logger. Attach the logger to the calculator.
4. Press the APPS button on the 3rd row on the calculator.
5. Start by pressing the number which is in front of DataMate on the screen.
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JSSS Round 2
Student
6. Press the CLEAR button and wait for the screen to settle.
7. Select SETUP from the main screen by pressing 1.
8. Using the blue cursor key
on the right, move the black arrow on the screen down to
MODE and press ENTER (bottom right on the calculator)
9. Select EVENTS WITH ENTRY from the SELECT MODE menu by pressing 3.
10. Select OK by pressing 1.
Procedure to obtain data
1. Hold the thistle funnel with its base under the water at the 10 cm mark on the graduated
cylinder.
2. Select the START by pressing 2.
3. Press ENTER.
4. Insert 10 as the value for depth and press ENTER.
5. Lower the thistle funnel so that its base is at the 20 cm mark.
6. Press ENTER.
7. Insert 20 as the value for the depth and press ENTER.
8. Continue the process for each graduation mark.
9. Press STO (on the left on the 2nd row from bottom) to finish collecting data. A set of
points appear on the screen.
To examine the graph
•
Press ENTER
•
Select ANALYZE by pressing 4.
•
Select CURVE FIT by pressing 2.
•
Select LINEAR (CH1 VS ENTRY) by pressing 1
The screen now shows the equation of the line: Y = A*X + B.
•
Press ENTER to see the best fit line for the data.
To repeat the process
•
Press ENTER
•
Select RETURN TO MAIN SCREEN by pressing 1.
The experiment can now be repeated if required.
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JSSS Round 2
Student
Conclusion
What is the relationship between pressure and depth in a liquid?
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
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JSSS Round 2
Student
To investigate the relationship between pressure and depth
for a liquid using a datalogger as a meter
OP11
Introduction
This investigation will examine pressure readings on a sensor when placed in a funnel of water at
different depths.
Apparatus
Datalogger, calculator, gas pressure sensor, long thistle funnel, piece of rubber tubing and
graduated cylinder
Gas pressure sensor
T
Thistle funnel
0
Calculator
10
Logger
20
30
40
Graduated
cylinder
Procedure
1. Connect the end of the thistle funnel to the pressure sensor using the piece of
rubber tubing.
2. Mark 10 cm intervals along the side of a 1000 cm3 graduated cylinder with the
zero mark near the top of the cylinder as shown. Fill the cylinder with water to the
0 cm mark.
3. Attach the gas pressure sensor to CH1 of the logger. Attach the logger to the
calculator.
4. Press the APPS button on the 3rd row of the calculator.
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JSSS Round 2
Student
5. Start the DataMate program by pressing the number which is in front of
DataMate on the screen.
6. Press the CLEAR button and wait for the screen to settle.
7. The value of the pressure can be read on the top right of the calculator screen.
Investigation 1
1. Hold the thistle funnel with its base under the water at the 10 cm mark on the graduated
cylinder. Read the pressure from the calculator screen.
2. Repeat this at 20 cm, 30 cm, etc., and fill in the table below.
Depth /cm
Pressure /kPa
Draw a graph of pressure against depth.
1. What is the relationship between pressure and depth in a liquid? _______________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
2. Using your graph, find the pressure when the depth is 0 cm. ___________________________
_____________________________________________________________________________
3. What is this pressure called? ____________________________________________________
_____________________________________________________________________________
4. Could this pressure have been measured in any other way? ____________________________
_____________________________________________________________________________
5. Try out your idea and write down your result. ______________________________________
_____________________________________________________________________________
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JSSS Round 2
Student
6. Use your graph to find the pressure at a depth of 1 m in water. _________________________
_____________________________________________________________________________
7. How much greater is the pressure at 1 m compared with the pressure at the surface of the
water?
_____________________________________________________________________________
8. Can you now predict what the pressure would be at a depth of 2 m in the water____________
_____________________________________________________________________________
9. Now predict what the pressure would be at a depth of 10 m in the water. _________________
Extension
Repeat the investigation using methylated spirits and compare the table of results with the table
obtained for water.
What was the pressure at a depth of 20 cm in water? ___________________________________
What was the pressure at a depth of 20 cm in methylated spirits? _________________________
What is the reason for the difference between the two readings?__________________________
_____________________________________________________________________________
Is there a difference between pressure in the water and the pressure in the methylated spirits at all
depths?_______________________________________________________________________
Can you see any pattern in the differences? __________________________________________
_____________________________________________________________________________
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JSSS Round 2
Teacher Support Material
To investigate the relationship between pressure and depth
for a liquid (Logger and Computer)
Apparatus
Logger, computer, gas pressure sensor, long thistle funnel, piece of rubber tubing and graduated
cylinder
Computer
Computer logger
Gas pressure
sensor
Thistle funnel
0
10
20
30
40
Graduated
cylinder
Procedure
1. Connect the end of the thistle funnel to the pressure sensor using the piece of rubber
tubing.
2. Mark 10 cm intervals along the side of a 1000 cm3 graduated cylinder and fill with water
to the 0 cm mark.
3. Attach the pressure sensor to CH1 of the computer logger. Attach the logger to the
computer.
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JSSS Round 2
Teacher Support Material
4. Start the logger program on the computer.
5. A screen appears with three windows.
6. Maximise the Meter Window on the top right of the screen - we now have a pressure
meter.
7. Hold the thistle funnel with its base under the water at the 10 cm mark on the graduated
cylinder. Read the pressure from the computer screen.
8. Repeat this at 20 cm, 30 cm, etc. and fill in the table below.
Depth / cm
Pressure / kPa
10
20
30
Plot a graph of pressure against depth.
The questions on the student worksheets for the other methods can also be used here.
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