1. Dimensional Analysis-”Bridge”
The “Factor-Label” Method
Uses Conversions Factors (things that are equal) to cancel units.
Units, or “labels” are canceled, or “factored” out

2. Dimensional Analysis Steps: 1. Identify starting & ending units.
2. Line up conversion factors so units cancel.
3. Multiply all top numbers & divide by each bottom number.
4. Check units & answer.

3. Lining up conversion factors:
= 1
1 in = 2.54 cm
2.54 cm cm
1 =
1 in = 2.54 cm
1 in in

4. What is a conversion factor?
Any fraction (ratio) in which the numerator is equal to the denominator.
12 inches = 1 foot OR
12 inches:1 foot OR
12 inches
1 foot

5. Creating a “Bridge” 5feet inches
A bridge will take us from unit to the next…
Ex: How many inches are in 5 feet?
1. What is our beginning unit?
2. What is our ending unit?
3. What do we need to convert?
5feet
inches

6. Lets try a practice problem….
There are an average of 124 zombies per square mile. If the Walking Dead group has traveled a total of 7 square miles, how many zombies have they encountered?
What if Rick kills 40 zombies per square mile, how many did he kill?

7. Now a real measurement
Mrs. Wooley walks 2.8 miles per day. How many centimeters does she walk per day? How many centimeters does she walk in a month?
A person drinks eight glasses of water a day. Each glass contains 300 mL. How many mL of water will a person drink in 1 year?