Fluid Mechanics with teacher's notes

DTSI Graphics HRW—Holt Physics 2002 Page 351 CMYK
PROCEDURE
CBL AND SENSORS
Pressure and volume of a gas
2. Prepare a data table in your lab notebook with four
columns and nine rows. In the first row, label the first
four columns Volume (cm 3 ), Trial 1 Pressure (atm),
Trial 2 Pressure (atm), and Trial 3 Pressure (atm).
3. Set up the pressure sensor, CBL, and graphing calculator
as shown in Figure 9-28. Connect the pressure
sensor to the CH1 port on the CBL. Turn on
the CBL and the graphing calculator.
4. Start the program PHYSICS on the calculator.
Select option SET UP PROBES from the MAIN
MENU. Enter 1 for the number of probes. Select
the pressure sensor from the list. Enter 1 for the
channel number. Select USE STORED from the
CALIBRATION menu. Select ATM from the PRES-
SURE UNITS menu.
5. Select the COLLECT DATA option from the MAIN
MENU. Select the TRIGGER option from the
DATA COLLECTION menu.
6. Turn the stopcock so that the valve handle points
downward. This will allow the syringe to fill with
air. Pull the plunger on the syringe to the 10 cm 3
mark. Turn the stopcock so that the valve handle
points upward to set the volume of air in the
Copyright © by Holt, Rinehart and Winston. All rights reserved.
syringe to 10 cm 3 . Attach one end of the tubing to
the end of the syringe and attach the other end to
the pressure sensor.
7. Slowly push in the plunger until the volume of air in
the syringe is near 8 cm 3 . Press TRIGGER on the
CBL to collect the pressure reading at this volume.
Record the reading from the CBL under Trial 1 Pressure
in your data table. Read the volume, and record
it in your data table. Select CONTINUE from the
TRIGGER menu on the graphing calculator.
8. Slowly push in the plunger until the volume of air
in the syringe is near 7 cm 3 . Press TRIGGER on the
CBL to collect the pressure reading. Record the
reading under Trial 1 Pressure in your data table.
Read the volume, and record it in your data table.
Select CONTINUE on the graphing calculator.
9. Repeat several times, decreasing the volume each
time by 1 cm 3 until the volume is 2 cm 3 .
10. Repeat steps 4–9 twice and record the new values in
the data table under Trial 2 and Trial 3.
11. Clean up your work area. Put equipment away safely
so that it is ready to be used again.
Analysis and Interpretation begins on page 353.
Figure 9-28
Step 6: Set the volume of air in the syringe and attach the tubing
securely to the syringe and pressure sensor.
Step 7: Record each volume in your data table, and use the
same volumes for each trial.
Step 9: Decrease the volume by 1 cm 3 until you reach 2 cm 3
or until the plunger will no longer move.
Fluid Mechanics
351
CHAPTER XX 9 LAB LAB
CBL and
Sensors Tips
◆ Students should have the program
PHYSICS on their graphing
calculators. Refer to Appendix B
for instructions.
◆ The CBL will measure the
pressure in atm (atmospheres).
Techniques to
Demonstrate
Demonstrate turning the stopcock
to operate the valve on the
syringe. Show students how the
valve works, and remind them
that it is important to open the
valve so that the pressure of the
initial volume of air is the same
as the pressure of the air in the
room. Demonstrate how closing
the valve seals the syringe to keep
the air in the syringe throughout
the experiment.
Checkpoints
Step 6: Make sure students
attach the tubing securely.
Step 7: Remind students to
record both the volume and the
pressure readings. Make sure students
read the volume reading on
the syringe and do not simply
record the value given in the
procedure.
Step 9: Students may find that it
is easy to push the plunger in
beyond the 2 cm 3 mark. If so,
they may want to continue as far
as they can. However, do not
allow students to force the
plunger when it becomes
extremely difficult to push.
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