MeasurementsMeasurements

Earth ScienceEarth Science

International SystemInternational System

From the French From the French Le Systeme Le Systeme International d’UnitesInternational d’Unites….SI system.….SI system.

Used by all scientists around the Used by all scientists around the world to ensure all measurements world to ensure all measurements are consistent.are consistent.

Very simple to use! All units are Very simple to use! All units are easy to convert by simply moving easy to convert by simply moving the decimal (uses the power of 10)the decimal (uses the power of 10)

International SystemInternational System

LengthLength

Basic Unit: Basic Unit: metermeter Often measured with a _______ stickOften measured with a _______ stick Smaller units: Smaller units: centicentimeter, meter, millimillimetermeter Centi= one hundredth of a meterCenti= one hundredth of a meter

– 1 meter = _____________ cm1 meter = _____________ cm Milli= one thousandth of a meterMilli= one thousandth of a meter

– 1 meter = _____________ mm1 meter = _____________ mm

LengthLength

Larger Unit: kilometerLarger Unit: kilometer Kilo = 1000 metersKilo = 1000 meters 1 kilometer equals 0.62 miles1 kilometer equals 0.62 miles A 10 km road race = 6.2 miles!A 10 km road race = 6.2 miles!

LengthLength

Different lengths require an Different lengths require an appropriate unitappropriate unit

What unit would you use to measure What unit would you use to measure the following: the following: – Distance from home to Distance from home to

school_____________school_____________– Distance around a track_________________Distance around a track_________________– Length of a pencil______________________Length of a pencil______________________– Width of a pencil______________________Width of a pencil______________________

MassMass

Measure of the AMOUNT OF Measure of the AMOUNT OF MATTER in an object. MATTER in an object.

Basic unit: Basic unit: GramGram Mass depends on the number and Mass depends on the number and

kinds of atoms – Measured using a kinds of atoms – Measured using a balance.balance.

Kg-used for large items, such as a Kg-used for large items, such as a car/personcar/person

G-used for smaller objectsG-used for smaller objects

VolumeVolume

The amount of space an object takes The amount of space an object takes upup

Basic Unit: Basic Unit: cmcm3 3 or or mL mL (milliliter) (milliliter) 1 cm1 cm33 = 1 mL….they take up the = 1 mL….they take up the

same amount of space.same amount of space. 2 different ways to calculate volume 2 different ways to calculate volume

depending on whether or not the depending on whether or not the specimen is a regularly or irregularly specimen is a regularly or irregularly shaped objectshaped object

VolumeVolume

Regularly-shaped objects: have Regularly-shaped objects: have smooth solid side, with a definite smooth solid side, with a definite geometric shapegeometric shape

Volume=Volume=LLength x ength x WWidth x idth x HHeight eight (LxWxH)(LxWxH) 2cm x 2cm x 2cm =

8cm3

VolumeVolume

Irregularly-shaped objects have Irregularly-shaped objects have no defined shape, such as a rock.no defined shape, such as a rock.

Uses the water displacement Uses the water displacement methodmethod 1. Record Initial volume

2. Insert object3. Record Final volume4. Subtract: V = F – I

9 mL – 2 mL = 7 mL…..or 7 cm3!-always measure at the bottomof the meniscus!

DensityDensity

Defined as mass per unit of Defined as mass per unit of volume….or how much mass is in a volume….or how much mass is in a given space.given space.

How tightly “packed” the atoms are.How tightly “packed” the atoms are. The higher the density, the tighter The higher the density, the tighter

the molecules are packed together, the molecules are packed together, more mass in a given space.more mass in a given space.

Calculated: Calculated: DDensity = ensity = MMass / ass / VVolumeolume Units: g/cmUnits: g/cm33 or g/mL or g/mL

DensityDensity

Suppose a substance has a mass Suppose a substance has a mass of 10 g and a volume of 10 ml of 10 g and a volume of 10 ml

D = m/vD = m/v D = __________ / ____________D = __________ / ____________ D = 1 g/ml…this is pure water, D = 1 g/ml…this is pure water,

which always has a density of 1 which always has a density of 1 g/mlg/ml

DensityDensity

Density is a physical property! It Density is a physical property! It always stays the same, no matter always stays the same, no matter the size of the object. the size of the object.

If you break an object in half, If you break an object in half, each half will have each half will have less mass less mass ANDAND less volume less volume than the object than the object as a wholeas a whole

Therefore, the density will still Therefore, the density will still calculate to be the same.calculate to be the same.

DensityDensity

Example: A rock with a mass of Example: A rock with a mass of 16 g and a volume of 8 ml has a 16 g and a volume of 8 ml has a density of 2 g/mldensity of 2 g/ml

D= m/v D = 16g/8ml = 2 g/mlD= m/v D = 16g/8ml = 2 g/ml If the rock is broken in half, each If the rock is broken in half, each

piece would have half the mass piece would have half the mass and volume as the originaland volume as the original

DensityDensity

Rock A= 8g & 4 ml Rock B = 8g & 4 Rock A= 8g & 4 ml Rock B = 8g & 4 mlml

Although the rock is now smaller, the density stays the same!

Density is a physicalProperty

Can be used to identifyan object

DensityDensity

Objects of different densities will Objects of different densities will separate, with the highest density on separate, with the highest density on the bottom, and the lowest density on the bottom, and the lowest density on the top.the top.

EX: layers of the earth. The core has EX: layers of the earth. The core has the highest density, its in the center. the highest density, its in the center. The crust has the lowest density, its on The crust has the lowest density, its on the surface. As you go up from the the surface. As you go up from the core, density decreases with each layer.core, density decreases with each layer.

DensityDensity

Density of water Density of water =________________=________________

If an object is greater than 1 g/ml, If an object is greater than 1 g/ml, then it will sinkthen it will sink

If an object is less than 1 g/ml, If an object is less than 1 g/ml, then it will float.then it will float.

Is ice greater or less than 1 g/ml?Is ice greater or less than 1 g/ml?

DensityDensity

Indicate whether the following Indicate whether the following item would sink or float in water:item would sink or float in water:

1.1. WoodWood D=0.67g/mlD=0.67g/ml__________________

2.2. Golf BallGolf Ball D=4.2g/mlD=4.2g/ml __________________

3.3. Ping PongPing Pong D=.36g/mlD=.36g/ml__________________

DensityDensity

If you know any two variables (m, If you know any two variables (m, v, or d), you can solve for the v, or d), you can solve for the other one.other one.

WeightWeight

Measures the Measures the forceforce of attraction of attraction between two objects due to between two objects due to gravitygravity

On earth, your weight is a On earth, your weight is a measurement of the earth’s gravity measurement of the earth’s gravity pulling down on your mass.pulling down on your mass.

Unit: Newton (pounds in this country)Unit: Newton (pounds in this country) Measured with a scaleMeasured with a scale

WeightWeight

The force of gravity (weight) depends The force of gravity (weight) depends on on massmass and and distancedistance

The more massive an object, the more The more massive an object, the more it will weigh. it will weigh.

The closer two objects are, the more The closer two objects are, the more they will weigh.they will weigh.

You actually weigh less on a mountain You actually weigh less on a mountain than at sea level! Why?than at sea level! Why?

You’re farther from the center of the You’re farther from the center of the earth!earth!

WeightWeight

The moon is much smaller than the The moon is much smaller than the earth, & therefore is made of much earth, & therefore is made of much less mass (matter). You would less mass (matter). You would weigh 1/6weigh 1/6thth of what you weigh on of what you weigh on earth!earth!

Since Jupiter is much larger than Since Jupiter is much larger than Earth, you would weigh a great deal Earth, you would weigh a great deal more! Too heavy to move even.more! Too heavy to move even.

Review-fill in the Review-fill in the following formulasfollowing formulas

Mass =Mass =

Volume = Volume =

Density = Density =

Percent ErrorPercent Error

Accepted Value – Measured Accepted Value – Measured Value Value

Accepted ValueAccepted Value

X 100

ReviewReview

Terms to know:Terms to know: LengthLength MassMass VolumeVolume DensityDensity WeightWeight Water displacement methodWater displacement method