Dimensional Analysis
Sometimes the information that you are given does not match the units of measure of the answer you are asked to find. In this case, you will have to do some conversions in order to find the answer in the correct units. You can use a procedure called dimensional analysis. This process allows you to ‘divide-out’ units of measure.
Here is an example:
The tires on a motorcycle have a diameter of 20 inches. If these tires turn at a rate of 1500 
, determine the motorcycle’s speed in mph, or 
. Round your answer to the nearest tenth.
First find the radius:
Since you are looking for linear velocity to be in mph, the radius needs to be written in miles. Using dimensional analysis:
Notice that feet and inches divide-out.
Next, the angular velocity needs to be written in hours:
