Transcript 03-Units

Basic Units
•Length meters
•Mass
kilograms
•Time
seconds
•TemperatureKelvin
•Amount Chm Mole
•Current
Ampere
•Luminous In Candela
Metric Prefixes
•Mega(M)
•Kilo(k)
•Milli(m)
•Micro(m)
Nano(n)
Centi(c)
Metric Prefixes
•(M) =
(n) =
3
•(k) = 10
-3
-2
•(m) = 10
(c) = 10
-6
•(m) = 10
6
10
-9
10
Accuracy
•How close you
are to the real
answer
Precision
•How well one can
repeat his or her
work
•Repeatability
Uncertainty
•All measurements have
a degree of unreliability
•Usually in the last digit
of a measurement
Significant Digits
•Meaningful
digits in a
number
Multiplication Uncertainty
• The answer should have the
same number of significant
digits as the multiplier with the
least number of SD
• Same for division
Addition Uncertainty
• When adding, line up decimal
place & add
• The decimal places in the
answer should = the least
• Same for subtraction
Determining Significance
• All non-zero digits
• All zeros between non-zero
numbers
• All trailing zeros if there is a
decimal place
Scientific Notation
•M x
•M = 1.00  M < 10.00
•n = an integer
n
10
Conversion Factor
• Ratio equal to one
• 12 inches/1 foot
• Multiply one unit by a
conversion to obtain another
unit w/o affecting magnitude
Convert:
•2.50 cm to Mm
•4.2 ns to ms
•3.15 kg to mg
Determine the length
in miles of a light year
• Light year = distance light
travels in one year
8
• c = 3.0 x 10 m/s
• 1 mile = 5280 ft
• 1 inch = 2.54 cm
Convert:
4.35 kg/L to mg/mL
2.31 mm/ns to cm/Ms
Calculate the volume
3
in m occupied by
750 kg of gas with
1.50 g/L
3
1 cm = 1 mL
Calculate the mass in kg of
a board that has
dimensions of 250 mm x
4
4.0 x 10 mm x 2.5 m and
had a density of 0.80 g/mL
3
1 ml = 1 cm
Calculate the density
3
of a 3.14 x 10 kg
cylinder that 5.0 m
long & has a diameter
of 2.0 m.
How many nm will
an object travel in
1/132 ks at
720 miles per hour
1 inch = 2.54 cm
1 mile = 5280 ft
Measurements
•Work problems
5 - 12 on page
23
Sig. Figs.
•Work problems
17 - 24 on page
23
Conv. Factors
•Work problems
28 & 36 on
page 24
Measurements
•Work problems
5 - 12 on page
25
Define all the key
terms on page 24
Work problems
13 - 16 on
page 25
Conversion
Factors
•Work problems
37 - 46 on page
25