Transcript Document

SI System
• Advantage of SI system is that it is based
upon the decimal system
• Units can be expressed in terms of small or
large units by changing the prefix.
• Prefixes are the same for all units
Magnitude and prefix
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1000
100
10
1
0.1
0.01
0.001
0.000,001
• kilo
• hecta
• deka
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deci
centi
milli
micro
Very small units
• 0.000,000,001
• 0.000,000,000,001
• nano
• pico
SI unit of mass is the kilogram
• Only unit where base unit has a prefix
• 1kg=1000g= 103g
SI unit of length Meter
• Kilometer used to measure long distances
• Smaller distances use centimeter 1/100, or
millimeter 1/1000, or micrometer
1/1000000
SI Unit of Area
• Area not a fundamental unit, derived unit,
derived from length
• Unit m2 used or cm2
SI Unit of Volume
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Derived from length
m3 for smaller volumes cm3
Also use term liter
1ml=1cm3
1 liter = 1000 cm3
SI Unit of Time
• Unit of time is second (s)
• Smaller units of time millisecond 1/1000 s,
or microsecond 1/1000000 s
• Larger units use non-SI, hours, days, years
Exponential Notation
• Scientists sometimes deal with very large or
very small numbers. Use exponential
notation to describe these.
Examples
• Size of an atom 0.000,000,000,1m
or 1x10-10 m.
• Size of the Sun 1900000000 m
1x109 m
or
Density
• Density is made up of tow units, mass and
volume
• Density= mass/volume D=m/v
• Usually use units g/mL
Energy
• Energy is the ability to change matter either
physically or chemically
• Two types of energy- Potential and kinteic
Potential Energy
• Energy of position or arrangement
• Ex. Skier on top of a mountain, a piece of
firewood.
Kinetic Energy
• Energy due to motion
• Ex. skier going down a mountain, a burning
log on a fire
Temperature and Heat
• When two objects of different temperature
are brought together heat is transferred
between them
• Temperature-a measure of the kinetic
energy of the molecules, tells us which
direction heat will travel
Heat
• Heat-energy flowing from a warmer object
to a cooler object.
Temperature
• SI unit of temperature is the Kelvin (K).
• 0 K is the coolest temperature theoretically
possible, when all motion stops.
• Degrees Celsius °C more common.
• K and °C have same magnitude but
different starting points
• 0 °C is melting point of water
• 0K = -273.15 °C
SI Unit of Heat
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SI unit of heat is the Joule (J)
calorie is a more common unit (cal)
1 cal = 4.184 J
1 cal amount of heat needed to raise 1 mL
of water 1 °C .
• Food Calorie is actually 1 kcal