The Metric SystemThe Metric SystemThe “Language” of ScienceThe “Language” of Science

Why Use the Metric System?Why Use the Metric System?

All scientific measurements are All scientific measurements are made using the made using the Metric SystemMetric System

Called the “Called the “SISI SystemSystem,” or - - ,” or - - ““LaLa SSystemeysteme IInternationalnternational d’Unitesd’Unites”” It’s the It’s the simplestsimplest and and easiesteasiest

measuring system ever thought up!measuring system ever thought up!

What makes it so easy?What makes it so easy?

Based on Based on 1010 Multiply or divide by Multiply or divide by 1010 when when

changing unitschanging units It’s a It’s a decimaldecimal systemsystem Can you think of a system we use Can you think of a system we use

every day that is a every day that is a decimaldecimal system? system?

Metric UnitsMetric Units

LengthLength (how long)(how long) metermeter

VolumeVolume (how much space is inside)(how much space is inside) literliter

ForceForce (push or pull)(push or pull) NewtonNewton

MassMass (how much matter)(how much matter) gramgram

Temp. Temp. (amount of heat)(amount of heat)

°°CelsiusCelsius

TimeTime (how long it takes)(how long it takes) secondsecond

Metric “Prefixes”Metric “Prefixes”

kkiloilo

hhectoecto

DDekaeka

ddecieci

ccentienti

mmilliilli

10001000

100100

1010

1/10 (0.1)1/10 (0.1)

1/100 (0.01)1/100 (0.01)

1/1000 (0.001)1/1000 (0.001)

101033

101022

101011

1010-1-1

1010-2-2

1010-3-3

GreekGreek

prefixesprefixes

LatinLatin

prefixesprefixes

Can you think of other words that use these prefixes? Can you think of other words that use these prefixes?

decade, cent, centipede, century, millipede decade, cent, centipede, century, millipede

Converting or “Switching” UnitsConverting or “Switching” Units For example:For example:

1000 m = 1 km1000 m = 1 kmoror

1 km = 1000 m1 km = 1000 m How do we How do we convertconvert or or switchswitch units? units? If you’re converting to a If you’re converting to a smallersmaller unit: unit:

multiplymultiply by 10, 100, or 1000 by 10, 100, or 1000 If you’re converting to a If you’re converting to a largerlarger unit: unit:

dividedivide by 10, 100, or 1000 by 10, 100, or 1000

It takes practice! Here’s a shortcut rule: It takes practice! Here’s a shortcut rule: move the move the decimal pointdecimal point right or left! right or left!or, add or subtract a or, add or subtract a zerozero

Becoming Familiar with MetricBecoming Familiar with Metric

One reason people find the One reason people find the metric systemmetric system hard is hard is because the units are unfamiliar to thembecause the units are unfamiliar to them

Let’s make it Let’s make it easiereasier::

What’s a millimeter?

What’s a centimeter?

What’s a meter?

About the thickness of a paper clip or a coin

About the width of your little finger

About 3 feet, or one long step

Volume and CapacityVolume and Capacity

VolumeVolume = the amount of space inside = the amount of space inside something something

CapacityCapacity = the amount of liquid a container can = the amount of liquid a container can hold (based on its volume) hold (based on its volume)

Imagine a cube with sides of 1 dm x 1 dm x 1 dm: Imagine a cube with sides of 1 dm x 1 dm x 1 dm: What’s it’s What’s it’s volumevolume?? multiplymultiply L x W x H L x W x H

Volume = 1 dmVolume = 1 dm33

or 1 or 1 cubiccubic decimeter decimeterWhat’s it’s What’s it’s capacitycapacity? ?

1 dm1 dm33 holds holds 1 liter1 liter of liquid of liquid (1 dm(1 dm33 is is 1 liter1 liter!)!)

Volume and CapacityVolume and Capacity Here’s what we mean:Here’s what we mean:

1 dm1 dm33 (or 1000 cm (or 1000 cm33) ) holdsholds 1 liter1 liter

1 cm1 cm33

holdsholds 1 milliliter1 milliliter

1 dm or 10 cm

1 cm

1 liter

1 ml

Mass and WeightMass and Weight MassMass = the amount of matter in an object= the amount of matter in an object

(measured in (measured in gramsgrams or or kilogramskilograms)) WeightWeight = the force of gravity on = the force of gravity on mass mass

(measured in (measured in NewtonsNewtons))

Your Your massmass can’t change, but your can’t change, but your weightweight depends depends on gravity:on gravity:• On the moon (only 1/6 On the moon (only 1/6 Earth’sEarth’s gravity), gravity),

a 180-pound astronaut only a 180-pound astronaut only weighsweighs about about 30 pounds.30 pounds.

• But, his But, his massmass is exactly the same as on Earth! is exactly the same as on Earth! (he’s made of the same amount of matter no (he’s made of the same amount of matter no matter where he is)matter where he is)

What is Density?What is Density? Objects with the same Objects with the same volumevolume can have different can have different massesmasses..

If more and more mass is crammed into the same space, an If more and more mass is crammed into the same space, an object is object is denserdenser..

So what So what isis densitydensity? How do we figure it out?? How do we figure it out?DensityDensity = = massmass ÷ ÷ volumevolume

If we know both the If we know both the massmass and the and the volumevolume of an object, we of an object, we can divide mass by volume to get the can divide mass by volume to get the densitydensity..

Density is described using a combination of units:Density is described using a combination of units:grams grams perper cubic centimeter cubic centimeter or or (g/cm(g/cm33))

Measuring DensityMeasuring Density

1)1) First, use a triple beam balance to find the First, use a triple beam balance to find the massmass in in gramsgrams. . Calibrate!!Calibrate!!

2)2) Next, use a graduated cylinder filled with Next, use a graduated cylinder filled with water to measure the water to measure the volume volume in in cmcm33::

An object placed in the container will An object placed in the container will displacedisplace, or , or push push upup the water. the water.

If the water is pushed up by 10 ml, what is the object’s If the water is pushed up by 10 ml, what is the object’s volume?volume?

10 ml = 10 cm10 ml = 10 cm33 !! !! Discovered by Archimedes (Eureka!!!)Discovered by Archimedes (Eureka!!!)

3)3) Last, divide Last, divide massmass by by volumevolume to get the to get the density density in in g/cmg/cm33..

Review QuestionsReview QuestionsAnswer the following questions to check your understanding.Answer the following questions to check your understanding.

1.1. What makes the metric system so simple and easy to use, even What makes the metric system so simple and easy to use, even if we are not familiar with it?if we are not familiar with it?

2.2. Why is the metric system known as a decimal system?Why is the metric system known as a decimal system?3.3. What is the basic metric unit for length? mass? volume? etc.What is the basic metric unit for length? mass? volume? etc.4.4. Do you know each of the metric prefixes and what number or Do you know each of the metric prefixes and what number or

fraction they represent?fraction they represent?5.5. What are some familiar comparisons which help us to get a feel What are some familiar comparisons which help us to get a feel

for a millimeter? A centimeter? A meter? etc. for a millimeter? A centimeter? A meter? etc. 6.6. What is the shortcut rule for multiplying or dividing by 10?What is the shortcut rule for multiplying or dividing by 10?7.7. What is the difference between volume and capacity?What is the difference between volume and capacity?8.8. What is the difference between mass and weight?What is the difference between mass and weight?9.9. What is density? How are mass and volume related to density?What is density? How are mass and volume related to density?10.10. How does Archimedes’ work give us a method for determining How does Archimedes’ work give us a method for determining

the density of any object?the density of any object?