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 ______________________
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