instructional objective: 1.identify standards of measurements 2.learn about si units

Instructional Objective:1.Identify Standards of Measurements2.Learn about SI units

Standards of Measurements

Standard:Is an exact quantity that people agree to

use for comparison

International System of Units (SI Units)

*came from the French words “Le Systeme Internationale d’Unites”.

Are universally accepted and understood by Scientists

Each type of SI measurements has a base unit

© 1999 Heather Holliday

SI comes from the French La Systeme Internationale.SI and metrics use the same units and processes.

There are certain steps to follow whenconverting between units of metric measure:1--Use the following short cut chartk h da * d c m2--Find your original place on the chart by looking at the problem to identify the number with the unit (mark that place)3--Find your target place on the chart by looking at the problem to identify the number without the unit (mark that place differently)4--Count how many places you would need to move between the original and target places5--Always move your decimal in the direction you moved on the chart from the original to the target6--Rewrite the number given in the problem and apply steps 4 and 5 to the number7--Write the answer in the blank provided

SI Base UnitsQuantity Measured Unit Symbol

Length meter m

Mass kilogram kg

Time second s

Electric current ampere A

Temperature kelvin K

Amount ofsubstance

mole mol

Intensity of light candela cd

Common SI Prefixes

Prefix Symbol Multiplying factor

Kilo k 1000

Deci d 0.1

Centi c 0.01

Milli m 0.001

Micro u 0.000 001

Nano n 0.000 000 001

Now let’s see how wellyou can perform someconversions!!

Example problems

10 km = _____ dm0.1 hm = _____ m1cm = _____ hm0.01 m = _____ mm100 dg = _____ dag10 hg = _____ kg0.1 mg = _____ dg0.001 cg = _____ mg1 kg = _____ g0.01 dag = _____ cg

The centigrade (Celsius) scale

temperature (K) = temperature (°C) + 273.15

the melting point of water is = 0°C = 273.15 K

the boiling point of water is = 100°C = 373.15 K

reading a graduated cylinder

The boiling point*is the temperature at which the vapor pressure of a liquid is one

atmosphere.

*Units - K (Kelvin)

The Fahrenheit scale

the melting point of water = 32°F the boiling point = 212°F.

The SI unit of temperature is Kelvin (K). Noticethat there is no degree sign used with the abbreviation.

To covert from Celsius to Kelvin temperatures:C--> K + 273K--> C - 273

Celsius Kelvin FahrenheitFreezing: 0 273 32Boiling: 100 373 212

Dervied units: are combinations of SI units.Volume: amount of space occupied by an object.Volume=Length X Width X HeightV= l X w X hThis is used to calculate the volume of a cube andcombines three length measurementstogether.

Density: the mass per unit volume of a material.Density=Mass/VolumeD=m/VThis is a combination of units of mass and volume.

Density of the regular objectMass- find the mass of the objectusing a balanceVolume- To find the volume by measuring the length, width, and height. Then calculate density=mass/volume

Density of the irregular objectMass- find the mass of the unknownusing a balanceVolume- To find the volume, first measure the water that can immerse the irregular object in a graduated Cylinder. Then dropped the object in the cylinder and note the displacement measurement.Density = mass/volume.

Length- the basic unit of length is the meter.

Meter- SI unit of length - the distance between the doorknob and the floor.

Scientific Measurement

Volume- is the amount of space that something occupies.

Liter - SI unit for volume ....- A little more than a quart ... - Solid objects can have volumes in cubic centimeters

Scientific Measurement

Mass- is the amount of matter an object contains.

Kilogram- the basic SI unit for mass.About 2.25 pounds. A smaller unit is the gram.

Scientific Measurement

Easier to use because it is a decimal system

Every conversion is by some power of 10.

Much easier to use when doing calculations.

The Metric System

A metric unit has two partsA prefix and a base unit.prefix tells you how many

times to divide or multiply by 10.

The Metric System

Length - meter - mMass - gram - gTime - second - sTemperature- Kelvin (K) or

ºCelsius (ºC)Volume - Liter - L

SI Base Units

kilo k 1000 timeshecto h 100 timesdeca D 10 timeskilometer - equals 1000

meters or about 0.6 miles

SI Prefixes

deci d 1/10centi c 1/100milli m 1/1000centimeter - 1/100 of a meter

or less than half an inch

SI Prefixes

Line up from zero not the end of the ruler

Small numbered divisions are centimeters (parts are mm)

Measuring Length

0 1 2 3 4

Measuring VolumeUse a graduated cylinder.Hold it level with your eye.Read the bottom of the curve.

Measures in milliliters mL.A meniscus is the curvature of the surface of the water

10

20

30

Weight is a measure of the pull of gravity and, mass is the amount of matter.

The weight of an object can change, but an object’s mass is constant.

Mass vs Weight

Use a triple beam balanceFirst zero the balance.Then place object on pan.Then move largest weight first, until pointer tips to right and move back one notch.

Triple Beam Balance Use

Move next smallest weight, until pointer tips to right and move back one notch.

Move smallest weight, until pointer is at mid-position.

When balanced, add up the weights.

Triple Beam Balance Use

0 1 2 3 4 5 6 7 8 9 10

0 10 20 30 40 50 60 70 80 90 100

0 100 200 300 400 500

Triple Beam Balance

Press on button to turn on.If balance is not on zero, press

zero button.Place object on pan and,

record mass in grams.Turn balance off at end of lab

period.

Electronic Balance Use

how far you have to move on this chart, tells you how far, and which direction to move the decimal place.

Metric Conversions

k h D d c mmLg

Change 5.6 mg to kilograms.starts at milli position and

move six places to the left.

Metric Conversions

k h D d c mmLg

move the decimal point six places to the left 0.0000056

5.6 mg = 0.0000056 kg

Metric Conversions

k h D d c mmLg

Change 5.6 m to millimetersstarts at the base unit position and move three places to the right.

Metric Conversions

k h D d c mmLg

move the decimal point three to the right 5600.

5.5 m = 5600. mm

Metric Conversions

k h D d c mmLg

convert 25 mg to gramsconvert 0.45 km to mmconvert 35 mL to liters

Metric Conversions

k h D d c mmLg

Density- tells you how much matter is packed into a given volume.

Calculated by dividing mass by volume ( D = M ) . V

Scientific Measurement

Calculate the density of an object with a mass of 25 g & a volume of 5.0 mL.

.D = M = 25 g = 5.0 g/mL . V 5.0mL

Density Problem

Instructional Objective:1.Learn the metric system2.Learn the scientific notions

Review Questions:1. 4578hg to mg____________________2. 4.29cm to dkm ______________________