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Scientists all over the world need to ‘communicate’ with each other. To do this easily, they use the same system of measurement. This ‘system’ is known as the……. THE METRIC or INTERNATIONAL SYSTEM of MEASUREMENT (SI).
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Scientists all over the world need to ‘communicate’ with each other. To do this easily, they use the same system of measurement. This ‘system’ is known as the…… THE METRICorINTERNATIONAL SYSTEM of MEASUREMENT (SI)
THE BASIC UNIT OF THE ENTIRE SI SYSTEM IS THEMETER This fundamental unit is a bit longer than a yard.
To measureSMALLER distances, the METER is divided by a factor of ‘10’: EXAMPLES: • Decimeter (dm) = 1/10 of a meter • Centimeter (cm) = 1/100 of a meter • Millimeter (mm) = 1/1000 of a meter A 3 day old tadpole is 1.2 centimeters in length.
To measure LARGERdistances, the METER is multiplied by a factor of ‘10’: EXAMPLES: • Hectometer (hm) = 100 meters • Kilometer (km) = 1000 meters
THE BASIC UNITS USED FOR MOST LINEAR MEASUREMENT ARE THESE FOUR…… MILLIMETERS- very small measurements CENTIMETERS- small measurements METERS- large measurements KILOMETERS- very large measurements
SI units should NOT be ‘MIXED’. That is, you would not write ‘1 meter 21 centimeters’.You should write ‘1.21 meters’. Also, linear measurements should be written using DECIMALS. In most linear measurements, ONE DECIMAL PLACE is sufficient. Do NOT use FRACTIONS!
To obtain a unit of VOLUME in the SI System, scientists took a empty box that measured 10 cm. by 10 cm. by 10 cm. and called this…… ONE LITER
A LITERis also used with the prefix ‘MILLI’. Thus we have…… a MILLILITER to measure very small volumes.
This is a ONE LITER cube. 1/1000 th of it is 1 MILLILITER. This small cube is one milliliter. This large cube is oneliter.
A MILLILITER has the same volume as ONE CUBIC CENTIMETER. 125 cc’s Which means, milliliters (ml) and cubic centimeters (cc) can be interchanged. They both have the SAME volume!
Now……to get a unit for MASS, scientists took1 MILLILITER OF WATERand made that mass equal to1 GRAM! 1 ml of water = 1 gram
Again, PREFIXES can be used in front of a GRAM.The common ones are…… MILLIGRAM - very small masses KILOGRAM - large masses 1 ‘carat’ equals 200 milligrams
Before we leave MASS units, we need to consider one other thing…… MASS and WEIGHT are NOT the same!
‘MASS’ is the amount of ‘stuff’ in an object. It does NOT have anything to do with GRAVITY!
MASS does NOT change !It is measured in GRAMS.It’s the SAME everywhere in the universe.It does NOT depend on gravity.It is measured with a BALANCE. All these things’ masses stay the same, wherever they are!
WEIGHT CHANGES !It depends on GRAVITY.It is usually measured in ‘pounds’.It is measured with a spring scale.
and finally……THERE TWO TYPES OF MEASUREMENT IN SCIENCE QUANTITATIVE QUALITATIVE YOU WEIGH 100 POUNDS. AN ‘UGLY’ BABY?
1. QUANTITATIVE EXAMPLES: • 70 degrees Celsius • One inch of rain • 6.2 centimeters • 640 miles • She scored 26 points
2. QUALITATIVE EXAMPLES: • It’s nice out • It’s really hot • It’s raining cats and dogs • He’s good looking
Whenever possible…… QUANTITATIVEis preferred over QUALITATIVE in SCIENCE!
A QUICK SI REVIEW • 1. THE BASIC SI UNIT OF LENGTH IS A _____. • 2. 1/100th OF A METER IS _____. • 3. THE ‘SI SYSTEM’ USED TO BE CALLED _____. • 4. A ____ IS USED TO MEASURE VERY LARGE LINEAR DISTANCES. • 5. 1/1000th OF A GRAM IS ONE _____. • 6. ‘AREA’ IS FOUND BY MULTIPLYING _____. TIMES THE _____. • 7. THE BASIC SI UNIT OF MASS IS A _____. • 8. THE SMALLEST SI PREFIX USED DAILY IS THE_____. • 9. WEIGHT CHANGES WITH ______. • 10. THE BASIC SI UNIT OF VOLUME IS A ______.