No, not pie...we're talking numbers! Pi! π!

Much of the calculations and scientific analysis for engineering applications can be done using approximations and valid assumptions to simplify an otherwise grossly complicated problem. If you were to take into consideration every single force, large or small, that could possibly interact with the system that you’re investigating, then your analysis work would become overblown to mythic proportions, and you might end up running away in utter confusion. Typically in engineering analysis, you neglect anything that is insignificant compared to the “big picture.” For example, if you’re analyzing how a car reacts to sliding on ice, you would usually assume kinetic friction is negligible, even though it’s there on a very small scale compared to the car’s motion on the ice.

One common approximation that engineers use in their numerical analysis is for π (we have a post from a few weeks ago about the use of Greek letters in engineering). As you might already know, you cannot be exact with the value of pi because it is an irrational number. There are, of course, several different ways to approximate the value of pi. So instead of using 3.141592653589793238462643383279502884197169399… (continued indefinitely), we use a simple 3.14 for π when doing calculations. Most people (not just engineers) would make this approximation if they were faced with a problem involving π. Now, you may know some people who can recite several hundred digits of π right off the top of their heads, and while it is a pretty cool skill to have and does have the potential to amaze the heck out of people, there don’t seem to be many practical applications associated with it. A simple 3.14 is good enough for most problems in engineering. Of course, if you’re looking for a more exact solution to a problem, then you’ll need to tighten your approximations to allow for more accurate solutions.

For your edification, pi to as many digits as you may care to want; 1000 digits for example: http://www77.wolframalpha.com/input/?i=N[pi,1000]. Just change the 1000 to represent however many you want.

(Image from Wikipedia)