Transcript 2_1 Units and Measurementsx

Section 2.1
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Section 2.1 Units and Measurements
Section 2-1
• Define SI base units for time, length, mass, and
temperature.
• Explain how adding a prefix changes a unit.
• Compare the derived units for volume and density.
mass: a measurement that reflects the amount of matter
an object contains
Comprehension
Verbs
explain
interpret
outline
discuss
distinguish
predict
restate
translate
compare
describe
activities and products
draw pictures to show a particular event.
Illustrate what you think the main idea was.
Make a cartoon strip showing the sequence of
events.
Write and perform a play based on the story.
Retell the story in your words.
Paint a picture of some aspect you like.
Write a summary report of an event.
Prepare a flow chart to illustrate the sequence of
events.
Make a coloring book.
Units of Measurement
Article: 26, 48
Terms: 25
Mastering Concepts: 50 (52-57)
Lab: 28
copy table: p. 26 (2-1) and (2-2)
Practice Problems: 29 (1-3)
Homework:
Cornell Notes: 2.1
Section Assessment: 30(4-9)
Mastering Problems: 50 (72-74) 11 Stamps
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Section 2-1
Units
• Système Internationale d'Unités (SI) is an
internationally agreed upon system of
measurements.
• A base unit is a defined unit in a system of
measurement that is based on an object or event
in the physical world, and is independent of other
units.
Units (cont.)
Section 2-1
Units (cont.)
Section 2-1
m/1G
1m/10dm
Units (cont.)
Section 2-1
• The SI base unit of temperature is
the kelvin (K).
• Zero kelvin is the point where
there is virtually no particle motion
or kinetic energy, also known as
absolute zero.
• Two other temperature scales are
Celsius and Fahrenheit.
Derived Units (cont.)
Section 2-1
• Density is a derived unit, g/cm3, the amount of
mass per unit volume.
• The density equation is
density = mass/volume.
Mastering Concepts:
50(52-57)
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Mastering Concepts
52. Why must a measurement include both a number
and a unit? (2.1)
• The number gives you the quantitative value, and
the unit indicates what was measured.
53. Explain why scientists, in particular, need standard
units of measurement. (2.1)
• Scientists from different countries have different
languages and cultures but must be able to share
and compare data.
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54. What role do prefixes play in the metric system? (2.1)
• Prefixes give the magnitude of the measurement.
55. How many meters are there in one kilometer? In one
decimeter? (2.1)
• 1000; 0.1
56. What is the relationship between the SI unit for volume
and the SI unit for length? (2.1)
• The SI unit for volume is the cubic meter, m3, which is
equal to three SI measurements of length multiplied
together.
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Derived Units (cont.)
Section 2-1
• A more convenient measure is the liter
57. Explain how
temperatures on the
Celsius and Kelvin
scales are related.
(2.1)
• The sizes of the
units are equal;
°C + 273 = K.
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Displacement Volume
• It's the way to figure out the
volume of an irregular object. The
volume is the amount of water that
has been displace after putting in
the object.
• Displace: how water level changes
after adding an object
• The difference of initial and Final
volume
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Volume Displacement
• It's the way to figure out the
volume of an irregular
object.
• The volume is the amount of
water that has been displace
after putting in the object.
• Displace: how water level
changes after adding an
object
Density involves
• 2 quantities
– Grams (mass)
– Cubic centimeter (volume)
• one relationship
– Grams/cm3
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Practicing Problems
29(1-3)
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page 29 Practice Problems
1. A piece of metal with a mass of 147 g is
placed in a 50-mL graduated cylinder. The
water level rises from 20 mL to 41 mL. What
is the density of the metal?
Density = mass/volume
Volume = 41 mL – 20mL = 21 mL
Density = 147g/21mL = 7.0g/mL
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p.29 (2)
2. What is the volume of a sample that has a
mass of 20 g and a density of 4 g/mL?
Volume = mass/density
v o l u m e = density 20 g/4 g / m L =5 m L
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3. A metal cube has a mass of 20 g and a
volume of 5 cm3. Is the cube made of pure
aluminum? Explain your answer.
the density of the cube = mass/volume
= 20g/5cm3 = 4 g/cm3.
No; the density of aluminum is 2.7 g/cm3
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Mastering Problems: 50 (72)
Mastering Problems Density (2.1) Level
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72. A 5-mL sample of water has a mass of 5
g. What is the density of water?
Density= mass/ volume = 5 g/5mL = 1g/mL
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