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Volume Measurement Methods
Volume Measurement Methods
Volume is a 3D space occupied by an object.
There are various methods for measuring volume. Three of them are listed below:
Formula method
Water displacement method
Fill the cylinder with water (figure 1a). Read the water level and write down the measurement (1st column in the table). Then put the object into the cylinder (figure 1b). Read the water level and write down the measurement (2nd column in the table).
Figure 1a Figure 1b
The difference between the two measurements is the volume of your object; in this case, it is 20 mL.
Estimate the error. Remember about meniscus(figure 2).
Figure 2. Reading a meniscus
Density method
Density is a measure of how much mass is contained in a given unit volume.
density = mass / volume
or
d = m / V
Knowing that, we can easily find the volume as a quotient of mass and density.
V = m / d
To use this method, you have to know the density of the material that you are measuring.
Weight your object.
To calculate the volume, you can use the density calculator below. Choose an option of calculating volume, and plug in the mass and density values. Remember the units.
Measurement Error/Accuracy
Measurement Error/Accuracy
The measurement error is estimated as a half of a smallest subdivision of the instrument used to perform the measurement. For example, the smallest subdivision in the ruler shown below is 1mm. Hence, the measurement error/accuracy is 0.5mm. For a glass cylinder, the error/accuracy is o.5mL (see the picture below). Since the electronic caliper displays the measurement on a screen, the accuracy of a caliper is o.o1mm.
Significant figures - refer to the Research Assignment
Experimental procedure
Experimental procedure
1. The volume of a rectangular block
Step by step guide
Use a digital caliper or a micrometer to measure the dimensions of a block (see the tutorial videos below). Repeat the measurement at least three times. Calculate the average of your measurements. State the error of your measurement.
Attention
Attention
When you measure something yourself, make sure that you put down the ruler or take another one for the second measurement and close the caliper or a micrometer between the measuremeents. Reading the same measured value several times from the same instrument is not a repeated measurement.
Calculate the volume. Express the results of your measurement using the proper number of significant digits and indicating error.
Express the results of your measurement using the proper number of significant digits and indicating the measurement error.
2. The volume of a marble
Measure the value of a marble using two different methods. Calculate the percent difference between the results to compare the methods
Step by step guide
Use the water displacement method to measure the volume of a marble. To increase the precision of your measurement, you can submerge a few marbles in water in a measuring cylinder, find their volume, and divide it by the number of marbles.
Use the formula method to calculate the volume of a marble.
Calculate the percent difference between the results obtained using different methods
3. The volume of a wire
Determine the best way to measure the volume of a wire. USe that method to measure it.
Measure it using another available method.
Compare the results.
Presenting the results
Presenting the results
Always present the measured value, the accuracy, and the unit. Here is an example:
V = 8.0 ± 0.5 mL
For the scientific notation, put both the value and the error in parenthesis and then state the magnitude:
V = (7.79 ± 0.01)×103 mm3
Instead of using the scientific notation, you may chose using different units (this is the advantage of the prefixes in the metric system; 1 cm = 10 mm, and 1cm3 = 103 mm3).
V = 7.79 ± 0.01 cm3
Remember that the measured value and the accuracy/error must have the same number of decimal places. Presenting the results as
1 ± 0.05 mL
is not correct. You may add some decimal places behind the measured value:
1.00 ± 0.05 mL
Similarly, in
0.025 ± 0.01 mm3
the number of decimal places does not match (three in 0.025 and two in 0.01). Instead, you may present your results as
0.03 ± 0.01 mm3
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