Converting Units with Dimensional Analysis

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.

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

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

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

Practice Problem How many minutes are in 8 days? 11520

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