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Have you ever been to a
foreign country?
One of the most important
things to do when visiting
another country is to
exchange currency.
For example, one United
States dollar equals
1535.10 Lebanese Pounds.
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Whenever you exchange currency, you are
utilizing the scientific method of dimensional
analysis.
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Dimensional analysis is a problem-solving
method that uses the idea that any number or
expression can be multiplied by one without
changing its value.
It is used to go from one unit to another.
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A conversion factor, or a fraction that is equal
to one, is used, along with what you’re given,
to determine what the new unit will be.
 What
happens when you divide a
number by itself?
 What happens when you divide a
unit by itself?
 In both cases, you get the number
1.
 Dimensional analysis involves
multiplication and division.
inches feet

feet
miles
seconds hours

minutes seconds
inches

miles
hours

minutes
1.
2.
3.
4.
5.
Start with the given value.
Write the multiplication symbol.
Choose the appropriate conversion factor.
The problem is solved by multiplying the
given data & their units by the appropriate
unit factors so that the desired units remain.
Remember, cancel like units.
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You can write any conversion as a fraction.
Be careful how you write that fraction.
For example, you can write
60 s = 1 min
as 60s
or 1 min
1 min
60 s
To convert between units:
 Figure out what CONVERSION FACTOR
you need to perform your calculation

 There are 12 inches in 1 foot
 12 inches
or
1 foot
1 foot
12 inches
1.
Suppose there are 12 slices of pizza in one
pizza. How many slices are in 7 pizzas?
Given: 7 pizzas
Want: # of slices
Conversion: 12 slices = one pizza
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Check your work…
7 pizzas
1
X
12 slices
1 pizza
=
84 slices
2. How old are you in days?
Given: 17 years
Want: # of days
Conversion: 365 days = one year
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Check your work…
17 years
1
X
365 days
1 year
=
6052 days
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Most problems are not simple one-step
solutions. Sometimes, you will have to
perform multiple conversions.
Example: How old are you in hours?
Given: 17 years
Want: # of days
Conversion #1: 365 days = one year
Conversion #2: 24 hours = one day

Check your work…
17 years
1
X
365 days
1 year
X
24 hours
1 day
148,920 hours
=
12 inches
1 foot = _____
100 centimeters
1 meter = _____
16
1 pound = _______
ounces
60
1 minute = ______
seconds
60
1 hour = ________
minutes
Inches to feet
Minutes to hours
Meters to centimeters
inches
1
1 ft
12 in.
minutes
1
60 min
1 hr
meters
1
1m
100 cm
12 in.
1 ft
1 hr
60 min
100 cm
1m
Dimensional Analysis can also be used
for combination units.
 Like converting km/h into cm/s.
 Write the fraction in a “clean” manner:

km/h becomes km
h
› Kilo
 So 1 km = 1000 m
› Centi
› So 100 cm = 1 m
› Milli
 So 1000 mm = 1m

Be able to use a chart for the others!