Metric System

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## Metric System

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**Metric System**Measurement**Measurements**• The English system uses measurements • like feet, yards, miles, and gallons. • Also known as the International System of Units or the SI system**SI Units International System of UnitsBase Units**meter (m) gram (g) liter (L) Celsius (C) seconds (s) Length Mass Volume Temperature Time**Metric System**The metric system is a system of measurement based on the number 10 • Common SI prefixes: • Kilo- (k) means 1,000 • Hecto- (h) means 100 • Deka- (da) means 10 • Deci- (d) means 0.1 (one tenth) • Centi- (c) means 0.01 (one hundredth) • Milli- (m) means 0.001 (one thousandth)**Conversions between large and small quantities**K H D B d c m King Henry Died By drinking chocolate milk • This chart tells you three things: • How many places to move the decimal • In what direction to move the decimal • What base unit to use**K H D B d c m**Examples: 4.51 kg = ________g 4587m = _________mm 1.23 mL = ________L**Answers…**Kg HgDgg dgcg mg 4 5 1 0 4.51 kg = 4510 g**mdm cm mm**4587 0 0 0 4587m = 4,587,000mm**ldl cl ml**1 23 mL 0 0 0 1.23 mL = 0.00123 L**Lengthmeasure distance**• The basic unit or SI unit of length in the SI system is the meter (m). • To measure objects smaller than a meter scientists use the centimeter (cm) or the millimeter (mm) • 100 cm = 1 meter • 1000 mm = 1 meter • For larger measurements, scientists use kilometers. • 1000 m = 1 km • Measuredwith a metric ruler or meter stick**Massmeasures amount of matter**• The basic unit or SI unit of mass in the SI system is the gram(g). • To measure the mass of large objects you will use a unit known as a kilogram • It is useful in measuring the mass of bicycles, cars, or people. • To measure the mass of smaller objects you will use a unit known as the gram (g) • Measuredwith a balanceor digital scale • It is useful in measuring the mass of a paper clip, thumb tack, staple. • There are 1,000 grams in a kilogram.**Measuring Mass**Digital Scale Triple-beam balance**The Difference Between Mass and Weight**• Weightis a measure of the force of gravity acting on an object. • Measure weight by using a scale. When you stand on a scale gravity pulls you downward. However, if you weighed yourself on the moon you would weigh less. • Massis a measure of how much matter an object contains, it remains constant no matter where an object may be. Your mass is the same on the moon as it is on Earth. ** The weightof an object may differon the moon, or on earth, but the massstays the same****Measuring Volumeof Liquids**• Volumeis the amount of spacean object takes up. • To measure the volume of a liquid, you will use a base unit or SI unit known as a liter(L). • You can measure large liquid volumes in kiloliters (kL) • You can measure smaller liquid volumes in milliliters (mL) • 1,000 mL = 1 L • Measuredwith a graduated cylinder**Graduated Cylinder**• Scientists commonly use a graduated cylinder to measure liquid volumes. • The graduated cylinder is marked off in millilitersegments. • When liquid is poured into a graduated cylinder, the topsurfaceof the wateris curved. This curve is called the meniscus. To determine the volume of the water, you should readthe bottomof the meniscus**Volume of Rectangular Solids**• The basic unit or SI unit to measure the volume of a solid object is a cubic centimeter (cm³) • A cubic centimeter is equal to the volume of a cube that measures one centimeter on each side. • 1 cm³ = 1 mL • For solids with larger volumes, scientists use the SI unit known as the cubic meter (m³). • A cubic meter measures one meter on each side. • Measured with a formula: Volume = length x width x height**Volume of Irregular Solids**• If you wanted to find the volume of an object that you could not determine the length, width, and height (example: rock), you would immerse the object in water and see how much the water levelrises. • You would subtract the amount of water that you started with from the amount of water that the object forced the water to rise to and you would know the volume of your object. • Known as water displacement**Density**• Density is a measure of how much mass is contained in a given volume. • To calculate density you divide the mass by the volume: Density = Mass Volume**Density**• Because density is actually made up of two other measurements – mass and volume - an object’s density is expressed in two units. • Two common units of density are grams per cubic centimeter (g/cm³) for regular solid items and grams per milliliter (g/mL) for irregular solid objects. • The numeratoris the measure of masswhile the denominatoris the measure of volume**Densities of Common Substances**Substance Density (g/cm³) Air 0.001 Ice 0.9 Water 1.0 Aluminum 2.7 Gold 19.3 The densityof an object stays the same no matter how large or small a sample of the substance is.**Density**• An object will floatif it is less dense than the surrounding liquid. • A piece of wood with the density of 0.8g/cm³ will float in water because the density of water is 1.0 g/cm³ • A ring made of pure silver with a density of 10.5 g/cm³ will sink in water because it is more dense.**Time**• Time is the period betweentwo events • The basic unit or SI unit of time in the SI system is the second(s). • Clocksand stopwatchesare used to measure time • Common Conversions for Time • 1s = 1,000 ms (milliseconds) • 1 min = 60 s • 1 h = 60 min**Temperature**• The measurement of how hot or cold something is (measurement of heat) • The basic unit or SI unit of temperature in the SI system is the Celsius scale (°C). • Water freezesat 0°C or 32°F • Water boilsat 100°Cor 212°F • Normal human body temperature is 37°C or 98.6°F • Temperature is measuredwith a thermometer. • Place the thermometer in a substance and wait for the liquid in the thermometer to stop moving. Then read the number next to the top of the liquid in the thermometer.