Fluid Mechanics with teacher's notes

ANALYSIS AND INTERPRETATION
Calculations and data analysis
1. Organizing data Using data from all three trials, make the following
calculations:
a. CBL and sensors Calculate the average pressure at each volume of
air in the syringe.
b. Boyle’s law apparatus Calculate the average volume for each level
of weight on the piston.
2. Organizing data Calculate the inverse of each of the pressures or volumes
from item 1.
3. Graphing data Plot a graph using the calculated averages from item 1.
Use a graphing calculator, computer, or graph paper.
a. CBL and sensors Graph Average Pressure versus Volume.
b. Boyle’s law apparatus Graph Average Volume versus Number
of Weights.
4. Graphing data Using a graphing calculator, computer, or graph paper,
make a second graph using the inverse averages from item 2.
a. CBL and sensors Plot a graph of the Inverse Average Pressure versus
Volume.
b. Boyle’s law apparatus Plot a graph of the Inverse Average Volume
versus Number of Weights.
Conclusions
5. Analyzing graphs Based on your graphs, what is the relationship
between the volume and the pressure of a gas held at a constant temperature?
Explain how your graphs support your answer.
6. Evaluating methods
a. CBL and sensors Because the pressure sensor was not calibrated to
your altitude, the pressure readings do not accurately reflect the
pressure of the gas in the syringe. Explain why calibrating the probe
is unnecessary for finding the relationship between the pressure
readings and the volume of the gas.
b. Boyle’s law apparatus In plotting the graphs, the number of
weights was used instead of the amount of pressure. Explain how the
weight on the piston serves as a measure of the pressure of the air
inside the syringe.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Fluid Mechanics
353
CHAPTER XX 9 LAB LAB
ANSWERS TO
Analysis and
Interpretation
CALCULATIONS AND
DATA ANALYSIS
1. a. For sample data, values
range from 1.14 atm to
2.19 atm.
b. For sample data, values
range from 15.17 cm 3 to
29.00 cm 3 .
2. a. For sample data, values
range from 0.457 atm −1 to
0.877 atm −1 .
b. For sample data, values
range from 0.0345 cm −3
to 0.0659 cm −3 .
3. a, b. Student graphs should
show a straight line
pointing down and to
the right.
4. a, b. Student graphs should
show a straight line
pointing up and to
the right.
CONCLUSIONS
5. At a constant temperature,
the volume of gas decreases
as the pressure increases.
6. a. CBL and sensors The
pressure sensor is able to
measure the difference
between one pressure
reading and another.
b. Boyle’s law apparatus
Students should recognize
that because equal masses
were used, the weight
applied to the gas is
directly proportional to
the number of masses.
The pressure is a direct
result of the weight.
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