Math in Science- Comparing Metric Units of Length

Math in Science- Comparing Metric Units of Length


In this tutorial, we’ll discuss meters as the base unit of length measurement and, using everyday objects as examples, try to give you an idea of the size and scale of various measurements based on meters. Let’s briefly review the metric staircase. Remember that as you move up the staircase, length measurements increase by factors of 10, and as you move down the staircase, length measurements decrease by factors of 10. Let’s begin with the basic metric unit of length – the meter. A meter is slightly larger than a yardstick, or about the length of a baseball bat. In the lab, scientists often deal with units of length that are smaller than meters. So let’s look at these smaller measurements next. Decimeters are 10 times smaller than meters. A decimeter is equal to one tenth of a meter, or about the length of a crayon. Centimeters are 100 times smaller than meters. A key on your computer keyboard is about a centimeter in length. Millimeters are a thousand times smaller than meters. A flea is about a millimeter in length, and ants are around 5 to 10 millimeters. Micrometers are a million times smaller than meters. Single cells are often measured in micrometers. A human skin cell is about 30 micrometers in diameter, while bacterial cells range in size from 0.5 to 5 micrometers. Micrometers are extremely small! In fact you would need a microscope to see something that small! Nanometers are even smaller at one billionth of a meter. Viruses are measured in nanometers. The ebola virus is about 970 nanometers in length (so almost a micrometer) but only 80 nanometers in diameter. Other viruses can be even smaller. They are so small that they require special electron microscopes to view. Let’s return to meters for a moment as the basic unit used to measure length. Scientists in the field often work with measurements that are larger than the meter, so let’s look at these larger units next. A decameter is ten times larger than a meter. This is about the length of a football field end zone. A hectometer is 100 times larger than a meter, or about the length of the entire field. Kilometers are 1000 times larger than a meter, or about the height of three empire state buildings stacked end to end. A megameter is a million times larger than a meter, or the equivalent of a 1000 kilometers. The distance from New York City to Chicago is a little over a megameter. A gigameter is equivalent to a billion meters. The mean diameter of the sun is about 1.4 gigameters. While it makes sense to understand all these units of measurement, the ones that are most commonly used in the sciences include: nanometer, micrometer, millimeter, centimeter, meter, and kilometer.

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