1. Units of Measurement
Why they are important...

2. ....like $125,000,000 important!
In 1999 NASA’s $125,000,000 Mars Climate Orbiter
space probe entered the Martian atmosphere burst
into flames and crash landed. It was entirely
destroyed.

3. A committee was formed to
investigate the crash.

4. They found that...
...the crash stemmed from a miscommunication
between the probes manufacturer and the
navigational team regarding units...
oLockheed Martin used English Units (inches, feet, pounds)
oThe Navigation Team used Metric Units (Meters, Newtons)

6. “This is going to be the cautionary
tale that will be embedded into
introduction to the metric system
in elementary school, high school,
and college science courses till the
end of time.”

7. English Standard Units
• You are probably familiar with these, they
include:
• Inches
• Feet
• Yard
• Mile
• Pounds
• Cup

9. What’s the problem?
The USA is the only major country in the world
that still uses English Standard Units.

11. The Metric System
• The rest of the world uses it.
• In the United States the Metric System is used by:
• Scientists
• Doctors
• Engineers
• Anyone who works with international clients
• Basically metric units are used for everything
except day-to-day life in America.
• Also known as SI or Systeme Internationale Units

13. The Metric System Is Easy!
• The Metric System is based upon Powers of
10.
– 1000 Millimeters in 1 Meter
– 10 Millimeters in 1 Centimeter
– 100 Centimeters in 1 Meter
– 1000 Meters in 1 Kilometer

14. But what about English Standard units?
• Unlike Metric units English Standard units are
based on complete randomness.
– They are so strange they
probably weren’t even
developed by a scientist
but rather a creepy guy
in a van.
Not really but it was way
funnier that way!

15. Seriously though, you’ll like the metric
system if you give it a chance!

16. Base Units
• The metric system uses certain fundamental
Base Units:
• Length = Meters
• Mass = Kilogram
• Volume = Liter
• Time = Second
• Temperature = Degrees Kelvin

17. Metric Units
Time: Unit Seconds: defined as time for a
certain excited atom (cesium) to make a
specified number of oscillations.
Length: Unit Meters: defined as distance light
travels in a specified fraction of a second.

18. Metric Units
One cubic meter is 1,000 liters.
One cubic meter of water has a mass of 1,000
kg, one metric ton, about 2,200 lbs.
Mass: Unit Kilogram: defined as
the mass of a chunk of platinum
in Paris, shown here.
Volume: Unit Liter: defined as
the mass of 1 Kilogram of water.

19. Metric Prefixes
If you need a larger or smaller unit, one can be
created by adding a prefix.

20. Learning Check
A rattlesnake is 2.44 m long. How long is the
snake in cm?
a) 2440 cm
b) 244 cm
c) 24.4 cm

21. English and SI Conversions
• If you know ONE conversion for each type of
measurement, you can convert anything!
• You must memorize and use these
conversions:
–Mass: 454 grams = 1 pound
–Length: 2.54 cm = 1 inch
–Volume: 0.946 L = 1 quart

22. Learning Check
A rider on RAGBRAI averages 18 miles per
hour what is their speed in kilometers per
hour?