METRIC SYSTEMMETRIC SYSTEM

THE INTERNATIONAL SYSTEM OF THE INTERNATIONAL SYSTEM OF MEASUREMENT USED BY SCIENTISTS (SI MEASUREMENT USED BY SCIENTISTS (SI SYSTEM)SYSTEM)

Making Scientific Measurements

When scientists make observations and measurements, it is not sufficient to say that something is “big” or “heavy”, “long” or “short.”

QualitativeMeasurements are general termsand are not specificenough for science.Examples include:Big, heavy, and

warm.

Quantitative Measurements

are specific and are the type of measurements scientists use. Examples include: 500cm3, 70g, and 100°C.

Quantity = #

UNITS OF MEASUREUNITS OF MEASURE

METRIC SYSTEM

LENGTH MASS VOLUME TEMPERATURE DENSITY

METERS GRAMS LITERS CELCIUSGRAMS

CC OR ML

Making Scientific Measurements

• Scientists use a standard system of measurement know as the: International System of Units (SI system).

• Each unit is 10 times larger than the next smallest unit.

Common SI prefixesCommon SI prefixes SymbolSymbol MeaningMeaningKilo-Kilo- k k 1,0001,000Hecto-Hecto- h h 100100Deka-Deka- da da 1010Deci-Deci- d d 0.1 one tenth0.1 one tenthCenti-Centi- c c 0.01 one 0.01 one hundredthhundredthMilli- Milli- m m 0.001 one thousandth0.001 one thousandth

SYSTEM IS BASED ON THE NUMBERSYSTEM IS BASED ON THE NUMBER

Length (distance)

Length is the: distance between two points.

FACTS ABOUT LENGTH MEASURMENTS:• The unit for distance is the meter (m).• Small distances measured in centimeters (cm) or

millimeters (mm)• Large distances (here to Richmond) measured in

kilometers (km)

1 km = 1000 m1 m = 100 cm1 m = 1,000 mm1 cm = 10 mm

Common Conversions

Temperature

Temperature is the: average motion of molecules in a substance.

Hot = faster motion Cold = slower motion

FACTS ABOUT TEMPERATURE MEASURMENTS:• The unit for temperature is a degree.• Scientists use the Celsius Scale °C to measure

temperature.• Water boils at 100°C and freezes at 0°C

00C TO C TO 00F (C X 1.8) +32F (C X 1.8) +3200F TO F TO 00C (F – 32) / 1.8C (F – 32) / 1.8

Thermometer

Area

Area is the: size of a region or space.

FACTS ABOUT AREA MEASURMENTS:• Area is found by multiplying two distances.• Area = (Length) x (Width)• Units are also multiplied and become “squared” 2

20 m

20 m

Length = 20mWidth = 20m

(20m) X (20m) = 400m2

Volume (square objects, like a box)

Volume is the: amount of space something takes up.

FACTS ABOUT VOLUME MEASURMENTS:• Volume is found by multiplying three distances.• Volume = (Length) x (Width) x (Height)• Units are also multiplied and become “cubed” 3

20 m

10 m10 m

Length = 10m Width = 10m Height = 20m

(10m) X (10m) X (20m) = 2000m3

Volume (liquid, like water in a cup)

FACTS ABOUT LIQUID VOLUME MEASURMENTS:• The unit for liquid volume is the Liter (L).• Volume is found using a graduated cylinder.• Units for small volumes are milliliters (ml).

You should always read a graduated cylinder at the bottom of the curve of the liquid. That curve is called the meniscus.

0

20

30

40

50

1 L = 1000 mL

Common Conversions

Volume of irregular shaped objects use water displacement

MASS (G)MASS (G)Mass is the: amount of matter “stuff” something is made of. Mass will not change unless you add or take away matter.

FACTS ABOUT MASS MEASURMENTS:The unit for mass is the gram (g).Large masses are measured in kilograms (kg).A triple beam balance (NOT A SCALE) is used to measure mass.

1 kg = 1000 g Common Conversions

Weight

Weight is: how much gravity pulls on you or on any other object, such as a planet.

Gravity changes from one place to anotherand thus so does your weight.

The more massive the object, the more it will pull on you...

AND THE HIGHER YOURWEIGHT WILL BE.

150 Newtons25

Newtons

You press down less on the scale.

MOON1/6 the gravity

Density

Density is: how closely packed particles in a substance are. Said another way, Density is: the amount of matter

(mass) in a given space (volume).

Density = mass (g) volume (cm3)

m= 10g m = 10gv = 10cm3 v = 2cm3

d= 1g/cm3 d= 5g/cm3

LESS DENSE MORE DENSE

Density

Density = mass (g) volume (cm3)

FACTS ABOUT DENSITY MEASURMENTS:• Density is found by dividing a mass (g) or (kg) and a

volume (cm3) or (ml).• Units must also be divided: Example: g/cm3.

Mass = 20g Volume = 10cm3

Density

Density = mass (g) volume (cm3)

• Given any two of these quantities (density, mass, or volume) you can find the other by either multiplying or dividing appropriately.

Density = 2g Volume = 10cm3

Mass = ?

(2g) x (10cm3)

m

d v