Measurement in Science

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Measurement in Science
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Customary Units vs. Metric Units
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What is a standard?
It is an exact quantity that people agree to use
for comparison.
Why are measurement standards important?
A meter in the U.S. is the same as a meter in
France.
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SI Units are...
International Standards
Abbreviated SI from the French Le Systeme
Internationale dUnites or the Common Name of
the Metric System
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Can you think about any situations that we use
the Metric System in our everyday life either
home or at school? Name at least 3
examples 1. 2. 3.
Come on brain!!
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Pros Cons of Metric System
Why should we use this system?

• Pros
• Easy based on the use of ten
• Conversions are easier - Just move decimal point
• Used all over the world not just USA

• Cons
• History of conflict all over the world
• People dont want to change
• Replacement cost of machinery to high

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What do all those prefixes mean?
International Standard Units (SI)
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Putting It All Together
prefix
symbol
unit
c
m
centi-
meter
(0.01)
hundredth of a meter
milli-
L
liter
m
(.001)
thousandth of a liter
kilo-
k
g
gram
(1000)
thousand grams
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How can I remember the order?
From LARGEST to smallest the easiest way to
remember the prefixes is in a sentence..
King Henry dances merrily down center
main. Or.. King Henry doesnt milk dairy cows on
Mondays.
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Metric Conversions
Step 1 Locate the DECIMAL POINT in the number
that you need to convert.
27.025 g _________ cg
Step 2 Mark the starting point (where the
decimal point is in the original number) on
the guide.
Kilo- Hecto- Deka- BASE deci-
centi- milli-
.
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Step 3 Mark the ending point (where the decimal
point is in the final number) on the guide
with an X.
Kilo- Hecto- Deka- BASE deci-
centi- milli-
.
X
This is the direction the DECIMAL will move.
27.025 g _________ cg
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Step 4 Move the decimal point (.) in the
direction of the X. Stop moving the decimal
when you reach the X. Thats how many
places you need to move the decimal point in
the original number.
X
27.025 g _________ cg
2702.5
27.025 g _________ cg
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SI Units for Measurement Used in Science
Metric ruler
Length / Distance
Measured in meters (m)
Volume
Regular Shape Length X Width X Height Measured
in cm3 Example box, land, table tops
Metric ruler
Irregular Shape Displacement Method Final
Reading Initial Reading Volume Measured in
milliliters (mL) Example Liquids, rocks, marbles
Graduated cylinder
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Continued - SI Units for Measurement Used in
Science
Mass
Balance
Measured in grams (g)
Temperature
Thermometer
Measured in degrees Celsius (OC)
Time
Clock
Measured in seconds (s)
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Density
the amount of mass in a given volume Formula to
calculate Density Units are expressed as -
g/mL density of a liquid - g/cm3 density of
a solid
Mass Volume
Density
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Using a Ruler
When measuring an object with a ruler, never
start at the 0 mark.
Rulers are less accurate due to wear and tear at
the ends.
Begin at the 2, 4, 5 or 6 cm mark in order to get
the most accurate mark.
What is the length of the red line? 6.2 cm or
1.2 cm
The red line would be 1.2 cm because the 5 is
the starting point.
6.2 5 cm 1.2 cm
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Reading the Meniscus
When measuring liquid volume in a graduated
cylinder, a meniscus often forms where the liquid
ends.
graduated cylinders
In order to read this liquid volume, you must be
at eye-level to the level of the liquid.
You take the reading at the BOTTOM of the
meniscus.
The liquid level is 36.5 mL.
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Read these liquid volumes in mL
B.
A.
11.5 mL
76.0 mL