Support Engineers' Tool Kit

Unit conversion

 

Unit conversions are used frequently. Material properties, velocity, mass, acceleration, etc, can be presented in different units, depending on the data source. Except for a few values that the engineer is familiar, there is always the question: What is the conversion factor for this transformation?

 

unit.jpg For downloading and installing on your computer there are many free programs available. The Free Unit Converter – 2.11 (from Unit Conversion Inc.- that you can download here) is very easy to use, presents many significant digits and shows on the right of the window a table of the unit you are converting in all possible units used in different countries (an extra that we have not seen in other converters we have used before). Click on the icon for download.

 

If you do not want to install more programs on your computer, unit conversions can be also done online.

 

The following sites can be accessed:

 

http://www.onlineconversion.com/

http://www.onlineunitconversion.com/

http://www.convert-me.com/

 

A confusion on units resulted in the failure of an axle of a roller coaster train at the Tokyo Disneyland's Space Mountain in 2004, causing it to derail. The part was of wrong size due to a conversion from English units to Metric units. Other famous case is the one of the GIMLY GLIDER, a Boeing 767 that run out of fuel due to a confusion on units when refueled.

 

The article below, from http://articles.sfgate.com, is another case of confusion with units.

 

Simple Error Doomed Mars Polar Orbiter / Computer confused pounds, grams when determining its course

October 01, 1999|By David Perlman, Chronicle Science Editor

What's the difference between inches, pounds and miles on the one hand, and centimeters, grams and kilometers on the other?

The answer could have saved the $125 million Mars Polar Orbiter from destruction last week, if watchdog computers at NASA's Jet Propulsion Laboratory in Pasadena had only known about the discrepancy.

In an embarrassingly simple mistake, NASA officials said yesterday, the spacecraft burned up on impact with the thin Martian atmosphere because two navigation teams and their computers had confused English and metric units.