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Transcript
Chapter 2
Measurement
2C: TLW 1. Write numbers in scientific notation
2. Perform simple operations with numbers in
scientific notation
β€’ Scientific Notation or Standard Form
π‘Ž π‘₯ 10π‘˜ , 1 ≀ π‘Ž < 10 and k is and integer
a is between 1 and 10
Write in scientific notation.
β€’ 9 448 800 000
β€’ 0.000 000 053 04
Write as a decimal number
β€’ 1.45 π‘₯ 10βˆ’5
β€’ 3.016 π‘₯ 106
GDC and scientific notation
β€’ Use the EE button!
β€’ 870, 000 x 95, 000, 000
β€’
6.2 π‘₯ 103
8 π‘₯ 1012
β€’ P. 43 #1 - 10
2D: TLW convert between
International System (SI).
β€’ Base Units
Quantity
Name
Symbol
Distance
Meter
m
Mass
kilogram
kg
Time
Second
s
Electric Current
Ampere
A
Temperature
kelvin
K
Intensity of Light
Candela
cd
Amount of
substance
mole
mol
Derived Units– defined in terms of base units
Quantity
Name
Area
square meter
π‘š2
Volume
cubic meter
π‘š3
Mass
Gram
Velocity
meters/second
Angle
Symbol
g
Radian
(π‘š 𝑠 )
π‘šπ‘  βˆ’1
rad
Some More
Quantity
Name
Symbol
Force
newton
N
Pressure
pascal
Pa
Energy
joule
J
Power
watt
W
Frequency
hertz
Hz
Finally An Example
β€’ Density is defined as mass per unit volume.
an SI unit to represent density.
β€’ A newton is defined as the force which
accelerates a mass of 1 kg at the rate of 1
meter per second per second. Write as a SI
unit.
It wasn’t going to last long.
Quantity
Name
Symbol
SI equivalent
Time
minute
hour
min
H
60 s
3600 s
Mass
tonne
t
1000 kg
Capacity
liter
L
0.001 π‘š3
Area
hetare
ha
Angle
degree
⁰
Temperature
Celsius
⁰C
10,000 π‘š2
πœ‹
π‘Ÿπ‘Žπ‘‘
180
K – 273.15
Pressure
millibar
mb
100 Pa
Distance at sea
Nautical mile
Nm
1.852 km
Speed at sea
Knot
Kn
1.852 π‘˜π‘šβ„Žβˆ’1
Energy
Kilowatt hour
kWh
3.6 MJ
Smaller or Larger Multiples
milli
m
kilo
k
𝟏
𝟏 𝟎𝟎𝟎 𝟎𝟎𝟎 𝟎𝟎𝟎
1
10βˆ’6 =
1 000 000
1
βˆ’3
10 =
1000
103 = 1000
mega
M
106 = 1 000 000
giga
G
109 = 1 000 000 000
nano
N
πŸπŸŽβˆ’πŸ— =
πœ‡
micro
When writing the value of a measurement, the prefix used should give the
value as a measure between 0.1 and 1000. Which is why one nautical
mile is written as 1.852 km and not 1852 m.
Conversion in Metric
β€’ K
H D (l g m) d
c m
– King Henry drinks lime green milk dead cows make.
Convert 3540 mm into ________________ meters
Convert 7.14 kg into ___________ grams
Non Meteric Units
β€’ Write conversion as a fraction with what you
want to cancel in the denominator.
β€’ Convert 4 hours and 12 minutes into seconds
β€’ Convert 15 knots into kilometers per hour
β€’ Convert 16π‘šπ‘  βˆ’1 into π‘˜π‘šβ„Žβˆ’1
β€’ Convert 54 kWh into MJ
What do you think?
β€’ Does the use of SI notation help us to think of
mathematics as a β€œuniversal language”?
Exercises
β€’ P. 47 #1-9, Hint for #9: Use Example 7 on
page 46
2E Goal: TLW round numbers.
β€’ How is rounding numbers useful?
– Population count
β€’ We use to approximate answers.
β€’ Symbol: β‰ˆ π‘œπ‘Ÿ =
The Rules
1. Look right, if less than 5 round down
2. Look right, if greater than or equal to 5 round
up
β€’ Round to the nearest 10:
οƒ˜ 48
583
5705
Stop and try these
β€’ 2E.1 p. 48 #1-4
Rounding Decimals
β€’ A traffic survey showed that 1852 cars carried
4376 people. Which is more appropriate to
write people per car?
β€’ 2.362 850 972 or 2.4
β€’ Why?
Where to round?
β€’ You will be given a specific decimal place (d.p.)
or significant figure (s.f.)
β€’ Round to 1 decimal place (1 dp)
3.27
Round to 2 dp: 6.3829
Calculate to 2 dp
β€’ Use your GDC
β€’ (2.8 + 3.7)(0.82 – 0.57)
β€’ 18.5 βˆ’
12.2βˆ’4.3
5.2
Try These
β€’ P. 49 – 50 # 1-3
Significant Figures (sf)
β€’ To round off to n significant figures look at
(n+1)th digit
1. If (n + 1) digit is 0, 1, 2, 3, or 4 don’t change the
nth digit
2. If (n + 1) digit is 5, 6, 7, 8, 9 increase nth digit by
1
Delete all digits after nth digit, replacing with 0s if
necessary.
β€’ Round to 2 s.f.: 7.182
β€’ Round to 2 s.f.: 0.00132
β€’ Round to 1 s.f.: 423
β€’ Round to 3 s.f.: 4.057
β€’ IB exams round to 3 s.f. unless otherwise stated.
Exercises
β€’ P.51 #1-8
3H: Goal: TLW find error and percentage error.
β€’ Approximation is close but NOT equal to the
true value.
β€’ Estimation is a value found by
judgment/prediction instead of using accurate
measurement.
β€’ How do we account for this difference?
Error
β€’ Estimate the product: 38.7 x 5.1
β€’ Find the true value:
β€’ What is the approximation?
β€’ Error is the difference between our measurement and the
actual value.
– Error = 𝑉𝐴 βˆ’ 𝑉𝐸
Percentage Error
β€’ Usually error is represented as a percentage.
– Look at the size of the error and ignore the sign.
– Percentage Error: 𝐸 =
𝑉𝐴 βˆ’π‘‰πΈ
𝑉𝐸
π‘₯100%
β€’ You estimate a fence length to be 70 m
whereas its true length is 78.3 m. Find to 1
d.p.
– Error
– Percentage Error
β€’ Alan wants to lay carpet on his 4.2 m x 5.1 m lounge room floor. He
estimates the area of the lounge room by rounding to the nearest meter.
β€’ Estimate the area.
β€’ The carpet costs $39 per π‘š2 . Find the cost using Alan’s estimate.
β€’ Find the actual area.
β€’ Find the percentage error.
β€’ Will Alan have enough carpet to cover his lounge?
β€’ How should he have rounded?
Exercises
β€’ P. 22 #1-7
2J: TLW convert between different currencies.
β€’ Currency is the money of a country.
β€’ When you go to a different country with
different currency you must exchange it.
β€’ Exchange Rate = how much your money is
worth in a foreign currency.
– Rates are published and change all the time.
– Simple Currency Conversions : no commision and
no fees to pay for exchanging currency.
Exchange Rates
β€’ 1 British pound (GBP) = 1.65 Australian dollar (AUD)
β€’ Convert 40 GBP to AUD
β€’ Convert 500 AUD to GBP
Exchange Rate Table
Currency
converting to
Currency
converting from
Hong Kong
(HKD)
China (CNY)
Japan (JPY)
Hong Kong
(HKD)
1
0.817
9.885
China (CNY)
1.225
1
12.106
Japan (JPY)
0.101
0.083
1
That means 1 CNY = 12.106 JPY
β€’ Convert 2000 CNY to JPY
– Just like other conversions write as a fraction.
Hong
Kong
(HKD)
China
(CNY)
Japan
(JPY)
Hong
Kong
(HKD)
1
0.817
9.885
China
(CNY)
1.225
1
12.106
Japan
(JPY)
0.101
0.083
1
USD
GBP
CHF
USD
1
0.640
0.91
GBP
1.56
1
1.43
CHF
1.10
0.70
1
Write down the exchange rate from CHF to USD.
Exchange 3000 USD to GBP
Write down the exchange rate from USD to CHF
Exchange 10 000 francs to pounds
Exchange Rates and Graphs
β€’ The graph shows the relationship
between Australian dollars and
Great Britain pounds on a particular
day. Find
– The number of AUD in 250 GBP
– The number of GBP in 480 AUD
– Whether a person with 360 AUD could
afford to buy an item valued at 240 GBP.
Exercises
β€’ P. 65-66 #1 - 5