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Measurementin Science
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Customary Units vs. Metric Units
DISTANCEInches, Feet, Yards, Miles Meters
LIQUIDSCups,Pints,
Quarts, Gallons Liters
WEIGHT/ MASSOunces, Pounds,Tons Grams
TEMPERATURE
° Fahrenheit ° Celsius
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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 International StandardsStandards
Abbreviated SI from the French Le Systeme Internationale d’Unites 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
• Pro’s– Easy: based on
the use of ten– Conversions are
easier - Just move decimal point
– Used all over the world – not just USA
• Con’s– History of conflict
all over the world– People don’t want
to change– Replacement cost
of machinery to high
Why should we use this system?
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Prefix Symbol Factor Number Factor Word Kilo k- 1,000 Thousand
Hecto h- 100 Hundred Deka da- 10 Ten BASE m, l, g 1 One Deci d- 0.1 Tenth Centi c- 0.01 Hundredth Milli m- 0.001 Thousandth
International Standard Units (SI)
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centi- meter
milli- liter
kilo-gram
(0.01)
(.001)
(1000)
Putting It All Together
hundredth of a meter
thousandth of a liter
thousand grams
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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 doesn’t milk dairy cows on Mondays.
Kilo- Hecto- Deka- BASE deci- centi-milli-
Meter, Liter, Grams
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Metric Conversions
Kilo- Hecto- Deka- BASE deci- centi-milli-
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.
Decimal Point
.
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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
27.025 g = _________ cg
This is the direction the
DECIMAL will move.
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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. That’s how many places you need to move the decimal point in the original number.
1 2.Kilo- Hecto- Deka- BASE deci- centi-
milli- X
27.025 g = _________ cg
2702.5
27.025 g = _________ cg
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SI Units for Measurement Used in ScienceLength / Distance
Volume
Measured in meters (m)
Irregular Shape – Displacement MethodFinal Reading – Initial Reading = VolumeMeasured in milliliters (mL)Example: Liquids, rocks, marbles
Metric ruler:
Graduated cylinder:
Regular Shape – Length X Width X HeightMeasured in cm3
Example: box, land, table topsMetric ruler:
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Continued - SI Units for Measurement Used in Science
TimeMeasured in seconds (s)
Clock:
Temperature
Measured in degrees Celsius (OC)
Thermometer:
MassMeasured in grams (g)
Balance:
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……the amount of mass in a given the amount of mass in a given volumevolume
Formula to calculate Density:Formula to calculate Density:
Units are expressed as:Units are expressed as: - g/mL – density of a liquid- g/mL – density of a liquid - g/cm- g/cm33 – density of a solid – density of a solid
MassMassVolumeVolume
Density =Density =
DD
MM
VV
DensityDensity
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When measuring an object with a ruler, never start at the “0” mark.
Rulers are less accurate due to wear and tearwear and tear at the ends.
Begin at the 2, 4, 5 or 6 cm mark in order to get the most accurate mark.
Using a Ruler
The red line would be 1.2 cm1.2 cm because the “5” is the starting point.
What is the length of the red line? 6.2 cm or 1.2 cm
6.2 – 5 cm = 1.2 cm
5 6
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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 BOTTOMBOTTOM of the meniscus.The liquid level is 36.5 mL.
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Read these liquid volumes in mL:
11.5 mL76.0 mL
A. B.