One cornerstone value of science is sharing information. Scientists all over the world need to make sure that when they are sharing their data that they are talking about the same numbers and amounts. Scientists use SI units or Système international (d'unités), which is also known as the metric system. Here are some examples of SI units:
Mass – not the same as weight! It’s the amount of matter in something (g, kg)
Length – measures distance (m, km)
Area – measures the surface of something (cm2, m2)
Volume – amount of space (L, ml)
Temperature – how hot or cold something is ( ͦC)
Time – seconds, minutes, or hours
The metric system is a series of units centered around a basic unit with the other units differing by powers of 10.
For example, the basic unit of length is a meter. From largest to smallest some other units of length are: kilometer, hectometer, dekameter, meter, decimeter, centimeter, milimeter. All of these units differ by a power of 10. For example, If 1 dekameter is equal to 10 meters, and 1 hectometer is equal to 10 dekameters then 1 hectometer is equal to 100 meters. It sounds confusing, but it is easy to convert one unit of length into another by moving the decimal point. This is much easier than multiplying by 12 to convert inches into feet or multiplying by 36 to get yards!
Scientists must take measurements with tools to gather their numbers (data). Accuracy is how close to the true value a measurement is. Precision is how often you can repeat that measurement. The best measurements are both accurate and precise
Percent error is the percentage that the measurement is different from the true value.
For example, let's say that a student got 86 points on a 100 point test. Their percent error is 14%, or in other words that's the amount they got incorrect.
Measurements and Sig Figs
Scientific Notation