Making Measurements and Calculating Data

Chemistry is the study of matter. In chemistry, you learn about what makes up matter, the structure of matter, the properties of matter, and how matter reacts. Since you are surrounded by matter (anything that takes up space and has mass...which is just about everything including the air you are breathing), studying chemistry is important for your everyday life.

In all branches of science, measurements must be taken, analyzed, and then communicated with others. It is important to have a consistent way of communicating size, temperature, time, amount, shape, and more. The metric system is the standard system agreed upon by scientists. What is the metric system? It is actually the standard system for measuring used worldwide. Very small and very large objects are expressed as multiples of ten of the base unit. According to Anthony Carpi at VisionLearning, the metric system has been around since 1790. Although the metric system is not commonly used in the United States, scientists have gladly embraced it as a system to help them take exact measurements. What makes it so popular among scientists? To begin with, it is remarkably easy to use. In this course, you will be making measurements. Scientists make and use measurements all the time, but did you know that we also use measurements in our everyday lives? Take a minute to think about how many measurements you use each day. How much sugar should be added to make blueberry muffins? How fast do you drive? How much time will it take you to get home from school? How much money will it cost to buy a snack after school? When you think about the answers to these questions, you most likely think in units of the English system. In this course, you will be required to use the metric system. To get yourself more familiar with the metric system, start looking for metric units as you go about your day. Look at the labels on the food you eat and drink, the personal care and cosmetic items you use, the kilometers on your speedometer, and more.

**Comparing Measurements**
English	Metric
Miles	Kilometers
eet	Meters
Inches	Centimeters
Ounces	Grams
Pounds	Kilograms
Gallon	Liters
Pints	Milliliters

The Mars Climate Orbiter: A Multimillion-Dollar Mistake

image of Mars Climate Orbiter Although NASA declared the metric system as its official unit system in the 1980s, conversion factors remain an issue. The Mars Climate Orbiter, meant to help relay information back to Earth, is one notable example of the unit system struggle. The orbiter was part of the Mars Surveyor '98 program, which aimed to better understand the climate of Mars. As the spacecraft journeyed into space on September 1998, it should have entered orbit at an altitude of 140-150 km above Mars, but instead went as close as 57km. This navigation error occurred because the software that controlled the rotation of the craft's thrusters was not calibrated in SI units. The spacecraft expected Newtons, while the computer, which was inadequately tested, worked in pound forces; one pound force is equal to about 4.45 Newtons. Unfortunately, friction and other atmospheric forces destroyed the Mars Climate Orbiter. The project cost $327.6 million in total. Tom Gavin, an administrator for NASA's Jet Propulsion Laboratory in Pasadena, stated, "This is an end-to-end process problem. A single error like this should not have caused the loss of Climate Orbiter. Something went wrong in our system processes in checks and balances that we have that should have caught this and fixed it."

NASA's Constellation Program: A Possible Casualty of Metric/English Conversions

Another NASA-related conversion concern involves the Constellation project, which is focused mainly on manned spaceflight. Established in 2005, it includes plans for another moon landing. The Constellation project is partially based upon decades-old projects such as the Areas rocket and the Orion crew capsule. These figures and plans are entirely in English units, and converting this work into metric units would cost approximately $370 million.

Disneyland Tokyo: A Bumpy Blunder

Tokyo Disneyland's Space Mountain roller coaster came to a sudden halt just before the end of a ride on December 5, 2003. This startling incident was due to a broken axle. The axle in question fractured because it was smaller than the design's requirement; because of the incorrect size, the gap between the bearing and the axle was over 1 mm - when it should have been a mere 0.2mm (to picture this, imagine that the gap is the thickness of a dime, compared to what it's supposed to be, the thickness of two sheets of common printer paper.) The accumulation of excess vibration and stress eventually caused it to break. Though the coaster derailed, there were no injuries. Once again, unit systems caused the accident. In September 1995, the specifications for the coaster's axles and bearings were changed to metric units. In August 2002, however, the English unit plans prior to 1995 were used to order 44.14 mm axels instead of the needed 45 mm axels.

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