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Section 3: Measurement Why do scientists use a standard measurement system? What are the SI units of measurement for length, mass, volume, density, time, and temperature? A Standard Measurement System Using SI as the standard system of measurement allows scientists to compare data and communicate with each other about their results. SI units- based on multiples of 10. Length The basic unit of length in SI is the meter (m). Mass The SI unit of mass is the kilogram. Mass refers to the amount of matter an object contains. Weight Weight refers to the measure of the force of gravity on an object. Less gravity, less weight! Weight is measured in Newtons (we use pounds in USA) Volume Volume is the amount of space matter takes up The SI unit of volume is the cubic meter (m3). Volume of a regular solid is measured by multiplying length x width x height Volume • Volume of irregular solids must be measured by water displacement Density The SI unit for density is kilogram per cubic meter or kg/m3 Density = Mass Volume Density Because density is actually made up of two other measurements–mass and volume–an object’s density is expressed as a combination of two units. The density of a substance stays the same no matter how large or small a sample of the substance is. Time The SI unit of time is seconds. Some timepieces can measure within one one hundredth of a second! Temperature The SI unit for temperature is Celsius or Kelvin scale 0 K is called absolute zero and is equal to -273C Temperature Scientists use the Celsius and Kelvin scales to measure temperature. The Kelvin (K) is the SI unit of temperature. We will use Celsius! Water freezes at 0 degrees Celsius and boils at 100 End of Section: Measurement