Transcript Document

Sig Fig Rules
1) All non-zero digits are significant
2) All zeroes between significant digits are themselves
significant.
3) All digits of any* number containing a decimal are
significant.
4) Exception to number 3: For any numbers less than 1
(i.e., decimal numbers or fractions) zeroes between
the decimal point and the first non-zero number are
NOT significant.
5) For numbers greater than 1 trailing zeros are not
significant unless the number contains a decimal
(rule 3).
Practice
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726  ______ s.f. (Rule #1)
3608  ______ s.f. (Rule #2)
24,090,007  ______ s.f. (Rule #2)
230.  ______ s.f. (Rule #3, this is BAD form!)
230.0  ______ s.f. (Rule #3)
45.08  ______ s.f. (Rule #3)
670.003  ______ s.f. (Rule #3)
More practice
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0.0024  ______ s.f. (Rule #4)
0.000006750  ______ s.f. (Rule #4 & #3)
5.11 x 10-4  ______ s.f. (Rule #4)
2.600 x 10-8  ______ s.f. (Rule #4 & #3)
3,100,000  ______ s.f. (Rule #5)
3,100,000.000  ______ s.f. (Rule #5 & #3)
4.56 x 1016  ______ s.f. (Rule #5)
2.90 x 104  ______ s.f. (Rule #5 & #3)*
•If a number is expressed in sci. not. It is generally assumed that ALL the digits
•to the left of the multiplication sign are significant. This is essentially rule #3.
Terra
Giga
T
1012
Mega
kilo
G
M
k
109
106
103
base
milli
micro
nano
pico
fempto
m
µ
n
p
f
10-3
10-6
10-9
10-12
10-15
centi
C
10-2
What this chart means:
For big things:
1 Terrameter = 1012 Meters OR 10-12 Terrameters = 1meter
For little things:
1 micrometer = 10-6 Meters OR 106 micrometers = 1meter
Making conversions
Step 1: Write down a conversion factor between the two
types of things you are comparing. If you don’t know it,
look it up.*
*You will need to know your metric prefixes and their values
for the exam & the rest of the year!
Step 2: Use “railroad tracks” or “factor-label” method to set
up conversion formula. If you need to make multiple
conversions, set each one up one at a time.
Step 3: Multiply across the top, multiply across the bottom,
divide top by bottom. Answer. Include any units remaining
that did not cancel.
Practice
240 Mm = __________ m
240Mm 106 m

 2.4  108 m
1Mm
736 nm = ___________ m
Ans: 7.36 x 10-7 m
1 Mm = 106 m
More practice
6.42 m = ___________ km
Ans: 6.42 x 10-3 km
42 m = ___________ µm
Ans: 4.2 x 107 µm
Still more practice (the “hard” ones)
12.3 Gm = _____________ pm
1 Gm = 109 m
1 m = 1012 pm
12.3Gm 109 m 1012 pm


 1.231022 pm
1Gm
1m
60,000 fm = _____________ km
Ans: 6 x 10-14 km
1 fm = 10-15 m
1000 m = 1 km
Weird, multi-dimensional conversions
• PreAP packet number 8 on dim. analysis
wrksht.
1 mile = 1609 meters
12 mi/hr*s = ___________ m/s2
1 hr = 3600 seconds
12 mi 1609 m 1hr


 5.36 m / s ^ 2
hr * s
1mi
3600 s
PreAP Students:
• If you don’t know the conversion factor look it
up:
– In a book
– On the internet (wikipedia is good)
– On a website: http://www.onlineconversion.com
– “MultiConvert” app for smartphone
If you use the website or the app: don’t cheat.
Don’t go straight to the result, even if you can. This
does you no good on your upcoming test or in
general. Just use it to find the conversion factors.
You could also use it to check your work