1. Converting Units with Dimensional Analysis

2. Sample Problem How many seconds are in six years?
This problem can seem daunting at first because it requires many steps.
The steps are not complicated, but it is easy to lose track of the unit you converted into.
To help keep track of the units as they are cancelled, we have a method called Dimensional Analysis.

3. Sample Problem Have: 6 years Need: # of seconds
How many seconds are in six years?
ANALYZE: What information is given and what does the question ask for?
Have: 6 years
Need: # of seconds

4. Sample Problem How many seconds are in six years?
PLAN: What is the necessary sequence of steps to get from what you have to what you need?
years
days
hours
minutes
seconds

5. Sample Problem 189,216,000 sec How many seconds are in six years?
EVALUATE: Organize these steps as a series of fractions. Each fraction represents a relationship between 2 units. The units should cross-cancel when you multiply and divide to leave you with your final unit and final number.
 6 years
 365 days
 24 hours
 60 mins
 60 secs
 1 year
1 day 
1 hour 
1 min 
189,216,000 sec

6. Practice Problem
How many minutes are in 8 days?
11520

7. Practice Problem How many inches are in 4 miles? (1 mile = 1760 yards)
253440