what you'll learn...
Overview
Absolute Standards : An unit of measurement, widely accepted and used in reference to a standardized prototype.
Derived Standards : An unit of measurement that is defined using other absolute standards.
basics
We have studied about measuring length of an object. For example, the length of a stick is meter.
Meter is a standard unit to measure length.
Let us look at the basic words in the above :
The word length means "distance between two points" or distance-span.
The phrase "to measure" means "to find the size or amount of a quantity".
The phrase "standard unit" means "a reference that is accepted by all and represents the same amount for all"
The word "meter" means
• an unit of length as given by the distance-span between two points on the prototype metal-rod
• ten millionth of the distance between equator and the north pole
meter defined
The unit of length "meter" is specified in reference to the standard provided by the International System of Units.
A metal-bar of specific material and at specific temperature is kept in International Bureau of Weights and Measures. The distance between two markings on that bar is defined as the standard unit meter.
The definition of meter is also given in reference to distances that do not change and can be calculated or measured. For example, the distance between equator and north pole along a specific meridian is a constant. One ten-millionth of that distance is defined as one meter.
Another example is : Speed of light in vacuum is constant. So the distance traveled by light in vacuum in one in 300,000,000 seconds is one meter.
It is noted that the meter is defined independent of any other measures.
Meter is an example of an absolute standard. The word absolute means "existing independent and not relative to other". That is, the standard measure "meter" is defined independent of other measures.
absolute and derived
To understand absolute standards better, some examples for absolute standards are provided
• The unit of temperature, degree Celsius is defined based on: melting point of ice is and boiling point of water is .
• The unit of time, second is defined based on: A normal day consists of hours with minutes in an hour and seconds in a minute.
Comparing the above with the units that are not independent
• The unit of area, square meter, is derived from unit of length meter.
• The unit of speed, meter per second, is derived from units of distance (meter) and time (second).
Such standards are called "derived standards".
The word "absolute" means: existing independent and not relative to other. The word "absolute" is from a root word meaning free and unrestricted.
The word "derived" means: dependent and in reference to other. The word "derived" is from root word meaning to draw out and take from.
summary
Absolute Standards : An unit of measurement, widely accepted and used in reference to a standardized prototype.
Derived Standards : An unit of measurement that is defined using other absolute standards.
Outline
The outline of material to learn "Mensuration basics : Length, Area, & Volume" is as follows.
Note: click here for detailed outline of Mensuration (Basics).
• Measuring Basics
→ Introduction to Standards
→ Measuring Length
→ Accurate & Approximate Meaures
→ Measuring Area
→ Measuring Volume
→ Conversion between Units of Measure
• 2D shapes
→ Perimeter of Polygons
→ Area of Square & rectangle
→ Area of Triangle
→ Area of Polygons
→ Perimeter and area of a Circle
→ Perimeter & Area of Quadrilaterals
• 3D shapes
→ Surface Area of Cube, Cuboid, Cylinder
→ Volume of Cube, Cuboid, Cylinder