Decimals:
The Nature of the Metric System
Established in 1795, to include the meter,
liter, and gram. With prefixes of centi,
deci, deca, hecto, and kilo.
The decimal metric system has gone
unchanged as the basis for the modern
International System of Units or SI
for short, that we use in SCIENCE.
Why Decimals?
Which column would you rather add?
Inch – Pound Units
1 yard, 2 feet, 3-1/4 inches
1 foot, 11 3-14 inches
2 feet, 5-1/2 inches
3 yards, 1 foot, 6-5/8 inches
_______________________
? Yards, ? Feet, ? inches
6 yards, 2 feet, 2 -9/16 inches
Metric Units
1.607 meters
0.589 meters
0.749 meters
3.216 meters
_______________
? meters
6.161 meter
Why Decimals?
A room measures 15 ft 3-3/4 in by 21 ft 7-1/2 in
( 4.667 m by 6.591 m )
What is the floor area in square yards?
What is the floor area in square meters?
36.79 sq yds
30.76 sq meters
Why Decimals?
In designing a calendar you wish to divide an area of
7-1/4 in by 11 inches ( 184 mm by 279 mm)
into 35 rectangles;
That is divide 7-1/4 in by 5 and divide 11 in by 7.
What are the dimensions of each rectangle in inches?
What are the dimensions of each rectangle in millimeters?
1-29/64 in by 1-37/64 in
36.8 mm by 39.9 mm
Beakers - used for mixing volumes
Ranging from 600 mL to 100 mL
Graduated cylinders - used for measuring
liquid volume
100 mL, 50 mL, 25 mL, 25 mL, 10 mL, 10 mL
Read meniscus at eye level.
75 mL
Examples of 25 mL
Different cylinders each with the same
volume measured out.
10 mL
Different cylinders each with the same volume
measured out. How do these cylinders differ?
Flasks - used for liquid volume
Erlenmeyer, Florence - How do they
differ? How does the shape influence how it is used?
Read meniscus at eye level.
6.4 mL
6.4 mL
How do these cylinders differ?
Each line is calibrated to .5 mL
20.5 mL
20.5 mL
Why?
Irregular shaped solids
Volume of irregular shaped objects by the
displacement method.
Step 1: Calibrate cylinder and measure 15 mL
Step 2: Lower object in water.
Read new volume. 16 mL
Finding volume of rock
(irregular shaped object)
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Starting volume = 15 mL
Ending volume = 16 mL
Volume of object (rock) =
16 mL – 15 mL = 1 mL
Volume of irregular shaped objects by the
displacement method.
Step 1: Calibrate cylinder &measure 15 mL
Step 2: Lower object in water.
Read new volume. 16 mL
Finding volume of screw
(irregular shaped object)
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Starting volume = 15 mL
Ending volume = 16 mL
Volume of object (screw) =
16 mL – 15 mL = 1 mL
Volume of irregular shaped object using
displacement method– metal weight
Step 1: Calibrate cylinder and
measure 7.0 mL
Step 2: Lower object and read
volume = 8.2 mL
Finding volume of metal weight
(irregular shaped object)
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Starting volume = 7.0 mL
Ending volume = 8.2 mL
Volume of object (screw) =
8.2 mL – 7.0 mL = 1.2 mL
Using cylinder tips
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Takes practice
Read meniscus at eye level (use of a
background helps viewing)
Calibrate cylinder
Pour carefully and slowly
Use dropper to add in last few drops
Check calibrations and all measurements
Volume of regular shaped object
(rectangular prism)
Measuring length = 8.5 cm
Volume of regular shaped object
(rectangular prism)
Measuring width = 6.0 cm
Volume of regular shaped object
(rectangular prism)
Measuring height = 2.0 cm
Volume = L x W x H
=8.5 cm x 6.0 cm x 2.0 cm
= 102. cm3
Relationship between solid volume and liquid volume
1 cm3 = 1 mL
Relationship between solid volume and liquid volume
1 cm3 = 1 mL