Many properties of matter are quantitative; they are related to numbers.
The metric system contains the units used for scientific measurements.
SI units are a particular choice of metric units commonly used in scientific measurements.
The SI system contains seven base units from which all other units are derived.
Prefixes are used to indicate decimal fractions or multiples of units.
The SI base unit for length is meter.
Mass is the amount of matter in an object; the base unit of mass is kilogram.
Temperature is the measure of hotness or coldness of an object.
Temperature is a physical property that determines heat flow.
Heat always flows from substances of higher temperature to substances of lower temperature.
The Celsius scale is based on 0oC as the freezing point of water and 100oC as the boiling point of water.
The Kelvin scale is the SI temperature scale; one unit of Kelvin is equal to one unit of Celsius.
The absolute zero, or 0 K, is the lowest attainable temperature in Kelvin; it equals -273.15oC; the freezing point of water, 0oC, is equal to 273.15 K.
The Fahrenheit scale is not commonly used in scientific studies; 32oF is the freezing point of water and 212oF is the boiling point of water.
K = oC + 273.15 , oC = (5/9)(oF – 32) , oF = (9/5)(oC) + 32
Derived unit are determined by using the defining equation for the quantity and substituting the appropriate base units.
Volume is defined as length cubed.
Liter is the non-SI unit for volume; one liter equals one cubic decimeter (dm3).
Density is used to characterize substances; it is defined as the amount of mass per unit volume.
Densities depend on temperature; the density of water is 1.00 g/mL of 1.00 g/cm3.
No comments:
Post a Comment