Saturday, February 13, 2010
♥ Units and measurements
Without a widely accepted system of units of measurement our civilization could not exist. Imagine the chaos if there were no standards for the measurement of mass, length and time, for example.
Scientists identify quantities which describe the natural world. In order to decide how much of a particular quantity a given object has, for example, MASS, it is necessary to compare that object to the masses of other objects which have known masses, defined in terms of an agreed standard.
A unit is an established standard for a physical quantity against which particular examples of that physical quantity can be compared. The act of comparing a physical quantity to a unit is called MEASUREMENT and the MEASURE of a particular physical quantity is the ratio of that physical quantity to the unit. The measure is a numerical value. When we calculate, we manipulate the measure, not the physical quantity.
Scientists identify quantities which describe the natural world. In order to decide how much of a particular quantity a given object has, for example, MASS, it is necessary to compare that object to the masses of other objects which have known masses, defined in terms of an agreed standard.
The instrument used is called a BALANCE, shown above. A PHYSICAL QUANTITY can be defined in terms of the operations necessary to measure it. For example, the length of an object can be determined by comparing it to an object of known length, such as a ruler.
A unit is an established standard for a physical quantity against which particular examples of that physical quantity can be compared. The act of comparing a physical quantity to a unit is called MEASUREMENT and the MEASURE of a particular physical quantity is the ratio of that physical quantity to the unit. The measure is a numerical value. When we calculate, we manipulate the measure, not the physical quantity.5:45 PM
