... the SI System and Percent Error (9.21.10)

Today, we learned about the Different Prefixes that are used with SI Units. Prefixes are used to show a decimal multiple or a fraction of the unit. The SI System also uses many prefixes to represent very big and very small numbers. The SI system has 20 prefixes, but the ones stated in the chart below are the ones that we will use throughout the year. 

*Note: one prefix that was left out is fento (fm), which has a standard form of 10 to the power of -15 (10^-15)

We also covered Experiment Accuracy. The maximum accuracy of any measurement is one half (1/2) of the smallest division of the measuring device. For example, a ruler with measurements of millimeters (mm) has a maximum accuracy of ±0.5mm (plus or minus 0.5 millimeters). 

The last topic we covered this class is about Expressing Error. Error is a fundamental part of science. No matter how hard we try, we cannot escape error. And there are usually 3 reasons for error: 1) Physical Errors in a measuring device, 2) "Sloppy" measuring, 3) Changing ambient conditions. Now, there are 2 different possibilities for calculating error, Absolute Error and Percent Error

The way we calculate Absolute Error is the measure value minus the accepted value. This is the method that we will sometimes use.

*AbsoluteError = Measured - Accepted

With Percent Error on the other hand, we get the measured value minus the accepted value divided by the accepted value multiplied by one hundred. Confusing? Look below. 

Until next class my friends, live long, prosper, and do your blog because it counts for 20% of your grade :)

-Michael&Jerome