Factor Label
Cancellation
Copyright 1998 Bryan Aldrich 4th Street Software
1
Factor Label Cancellation
• sometimes known by other
names:
– FLC
– Conversion Factor Approach
– Dimensional Analysis
Copyright 1998 Bryan Aldrich 4th Street Software
2
Usefulness
• FLC is used to solve problems
which involve unit
conversions.
• Uses equivalences to get rid
of unwanted labels and
replaces them with the labels
which will lead to a correct
solution.
Copyright 1998 Bryan Aldrich 4th Street Software
3
Process
• Start with “what you know”.
• Draw a “times sign” and a line
to the right of your first entry.
• Fill in the top and bottom of
the fraction so that at least
one set of units will “drop out”
when multiplied.
Copyright 1998 Bryan Aldrich 4th Street Software
4
Process
• Make sure that the top and
bottom of the fraction are equal.
• If you need to, multiply additional
factors until all you have left are
the units you need.
• Multiply all the numbers in the
numerators and divide this by all
of the numbers in the
denominators.
Copyright 1998 Bryan Aldrich 4th Street Software
5
Example One
• Convert 45 miles to kilometers
(given: 1.6 km = 1 miles)
1.6 km
45 miles ×
= 72 km
1 mile
Copyright 1998 Bryan Aldrich 4th Street Software
6
Example Two
• Convert 16 ounces to grams
(given 1 ounce = 28
grams)
28 grams
16 ounces ×
= 448 grams
1 ounce
Copyright 1998 Bryan Aldrich 4th Street Software
7
Example Three
• Convert 5 pounds to grams
(given 1
pound = 16 ounces, 1 ounce =
28 grams)
16 ounces 28 grams
5 lbs ×
×
= 2240 grams
1 lb
1 ounce
Copyright 1998 Bryan Aldrich 4th Street Software
8
Example Four
• Convert 36 years to seconds.
365 days 24 hours 60 min 60 sec
36 years ×
×
×
×
= 1.1× 109 sec
1 year
1 day
1 hour 1 min
Copyright 1998 Bryan Aldrich 4th Street Software
9
Example Five
• Convert 60 miles per hour to
kilometers per hour (given 1.6
kilometer = 1 mile)
60 miles 1.6 kilometers
×
= 96 km / hour
1 hour
1 mile
Copyright 1998 Bryan Aldrich 4th Street Software
10
Problems
$8.25 = _?_ $Canadian
(assume $1 Am = $1.32 Can)
Copyright 1998 Bryan Aldrich 4th Street Software
11
Problems
47 lbs = _?_ grams
Copyright 1998 Bryan Aldrich 4th Street Software
12
Problems
226 miles = _?_ inches
Copyright 1998 Bryan Aldrich 4th Street Software
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