- The length of a piece of string can be measured by comparing the string against a meter stick.
- The volume of a drop of water may be measured using a graduated cylinder.
- The mass of a sample may be measured using a scale or balance.
- The temperature of a fire may be measured using a thermocouple.
Comparing Measurements
Measuring the volume of a cup of water with an Erlenmeyer flask will give you a better measurement than trying to gauge its volume by putting it into a bucket, even if both measurements are reported using the same unit (e.g., milliliters). Accuracy matters, so there are criteria that scientists use to compare measurements: type, magnitude, unit, and uncertainty.
Measurement Systems
Measurements are calibrated, which is to say they are compared against a set of standards in a system so that the measuring device can deliver a value that matches what another person would obtain if the measurement were repeated. There are a few common standard systems you may encounter:
- International System of Units (SI): SI comes from the French name Système International d'Unités. It is the most commonly used metric system.
- Metric System: SI is a specific metric system, which is a decimal system of measurement. Examples of two common forms of the metric system are the MKS system (meter, kilogram, second as base units) and CGS system (centimeter, gram, and second as base units). There are many units in SI and other forms of the metric system that are built upon combinations of base units. These are called derived units.
- English System: The British or Imperial system of measurements was common before SI units were adopted internationally. Although Britain has largely adopted the SI system, the United States and some Caribbean countries still use the English system for non-scientific purposes. This system is based on the foot-pound-second units, for units of length, mass, and time.
Answers & Comments
ANSWER:
- The length of a piece of string can be measured by comparing the string against a meter stick.
- The volume of a drop of water may be measured using a graduated cylinder.
- The mass of a sample may be measured using a scale or balance.
- The temperature of a fire may be measured using a thermocouple.
Measuring the volume of a cup of water with an Erlenmeyer flask will give you a better measurement than trying to gauge its volume by putting it into a bucket, even if both measurements are reported using the same unit (e.g., milliliters). Accuracy matters, so there are criteria that scientists use to compare measurements: type, magnitude, unit, and uncertainty.
Measurements are calibrated, which is to say they are compared against a set of standards in a system so that the measuring device can deliver a value that matches what another person would obtain if the measurement were repeated. There are a few common standard systems you may encounter:
- International System of Units (SI): SI comes from the French name Système International d'Unités. It is the most commonly used metric system.
- Metric System: SI is a specific metric system, which is a decimal system of measurement. Examples of two common forms of the metric system are the MKS system (meter, kilogram, second as base units) and CGS system (centimeter, gram, and second as base units). There are many units in SI and other forms of the metric system that are built upon combinations of base units. These are called derived units.
- English System: The British or Imperial system of measurements was common before SI units were adopted internationally. Although Britain has largely adopted the SI system, the United States and some Caribbean countries still use the English system for non-scientific purposes. This system is based on the foot-pound-second units, for units of length, mass, and time.
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