Derived SI Units, continued Density •Density is the ratio of mass to volume, or mass divided by volume. mass m density = D = volume V or Section 2 Units of Measurement Chapter 2 • The derived SI unit is kilograms per cubic meter, kg/m 3 • g/cm 3 or g/mL are also used • Density is a characteristic physical property of a substance.
Section 2 Units of Measurement. Chapter 2. Derived SI Units, continued Density. Density is the ratio of mass to volume, or mass divided by volume. The derived SI unit is kilograms per cubic meter, kg/m 3. g/cm 3 or g/mL are also used. - PowerPoint PPT Presentation
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Derived SI Units, continuedDensity
• Density is the ratio of mass to volume, or mass divided by volume.
mass mdensity = D =
volume Vor
Section 2 Units of MeasurementChapter 2
• The derived SI unit is kilograms per cubic meter, kg/m3
• g/cm3 or g/mL are also used • Density is a characteristic physical property of a
substance.
Derived SI Units, continuedDensity
• Density can be used as one property to help identify a substance
Section 2 Units of MeasurementChapter 2
Sample Problem A
A sample of aluminum metal has a mass of
8.4 g. The volume of the sample is 3.1 cm3. Calculate the density of aluminum.
Section 2 Units of MeasurementChapter 2
Derived SI Units, continued
Derived SI Units, continued
Sample Problem A Solution
Given: mass (m) = 8.4 gvolume (V) = 3.1 cm3
Unknown: density (D)
Solution:
mass density =
v
olume 3
3
82.
.4 g
3.7 g
1 cm/ cm
Section 2 Units of MeasurementChapter 2
Re-Arranging the Formula
Here is a method to help you re-arrange the formula to find another variable.
For example the density formula, which is D = m/v, can be rearranged to give the
formula for mass or volume.
Rearranging the formula, continued
Start by drawing a formula circle:
It should be divided into three sections by drawing a “T” in the middle. The horizontal part of the “T” represents the fraction bar.
Since the “M” is above the fraction bar
in the formula, it remains above the fraction
bar in the circle. The “D” and “V” will be written below the
fraction bar on either side of the vertical line.
M
D V
Rearranging formulas.
To find the formula for any of the given variables, cover that variable, and your formula remains. (This technique will work with any three variable equation involving multiplication or division)
When “M” is covered, When “D” is covered When “V” is covered
what remains is “DV” what remains is “M/V” what remains is “M/D”.
Therefore,
M = DV D = M/V V = M/D
M
D V
M
D V
M
D V
Density Practice Problems
Page 40 – Practice Problems (1-3)
Work these problems in your notebooks.
You will have 10 minutes to complete this exercise.