How heavy is a kilogram?
The Institute for Reference materials and Measurements defines the
kilogram as:
“The kilogram is a unit of mass, the measurement of which corresponds to the
general, everyday notion of how ‘heavy’ something is. (The kilogram is almost
exactly equal to the mass of one litre (liter) of water and was originally defined
as the mass of one litre (liter) of pure water at a temperature of 4 degrees
Celsius at standard atmospheric pressure” (4 degrees Celsius is the same as 39.2
degrees Fahrenheit).
We are accustomed to the notion of ‘liter’, but since we
are trying to be precise, then what exactly is one litre? A
liter is a unit of volume equal to fill an empty cube 10 cm
on each side (side wall thickness neglected).
For scientists around the world it is very important that a “master” kilogram be
kept weighting exactly the same no matter the surrounding conditions. They know
this is a physically impossible task, so the best they can do is to maintain one
“prototype kilogram” under the best controlled conditions. Duplicates of this
prototype kilogram are kept around the world to maintain uniformity when
defining weights.
The pound is another standard for “weight” (that is, “mass”). The pound is
widely used in the US and UK. Most of the countries of the world use the metric
system, upon which the kilogram is based.
1 pound = 0.4537 kg < --- > 1 kg = 2.2046 pound
Thus, one pound is a little less than half a kilogram, and one kilogram is little
more than twice a pound.
What weighs 1 gram? The Bureau of Engraving and
Printing of the U.S. Department of the Treasury
claims: “The approximate weight of a note,
regardless of denomination is (1) one gram”.
This is an important fact because moving apart from the
abstract and unreachable “prototype kilogram”, or its
international duplicates depicted in the figure above, 1 kg is
approximately 1,000 US paper currency bills. This fact may
also hold true for other countries’ currencies.
In everyday usage, "mass" is often used interchangeably with weight,
but weight and mass are different concepts. Weight is affected by the
gravitation factor on celestial bodies; weight can be zero if no
gravitational force is acting but mass can never be zero.
Sun
27.9
Gravitational factor for planets (Earth = 1)
Moon
Mars
Jupiter
0.17
0.38
2.54
Saturn
1.08
Ref. European Commission. Institute for Reference Materials and Measurements.
A stainless-steel one-kilogram
standard in its travelling case.
Kilogram to pound
conversion chart
Kilogram (kg)
Pound (lb)
10
22.0
25
55.1
50
110.2
75
165.3
100
220.5
120
246.6
140
308.6
160
352.7
180
396.8
200
440.9
Pound to kilogram
conversion chart
Pound (lb)
Kilogram (kg)
10
4.5
25
11.3
50
27.2
75
34
100
45.4
120
54.4
140
63.5
160
72.6
180
81.6
200
90.7
Simon Stevin (c. 1548-1620).
Flemish mathematician and
engineer. One of the earliest
proponents of a uniform decimal
system for measurements in his
book The Tenth.
© E. Pérez http://4DLab.info