Comment Re: 2 tons? (Score 2) 56
A pound is a unit of weight and can correspond to any kg mass, determined by the gravity of the place where it is being measured.
Weight is dependent on gravity, mass is not. Welcome to 5th grade science class
Which is why the metric system has separate units for mass and weight/force.
But that's not the case with the pound, it is used for both (sometimes, but not always more specifically as pound-force or pound-mass)
http://en.wikipedia.org/wiki/P...
The pound or pound-mass (abbreviations: lb, lbm, lbm, [1]) is a unit of mass used in the imperial, United States customary and other systems of measurement. A number of different definitions have been used, the most common today being the international avoirdupois pound which is legally defined as exactly 0.45359237 kilograms, and which is divided into 16 avoirdupois ounces.
Don't believe Wikipedia? How about the NIST?
http://physics.nist.gov/Pubs/S...
MASS and MOMENT OF INERTIA: To convert from pound (avoirdupois) (lb) to kilogram (kg)
http://physics.nist.gov/Pubs/S...
FORCE: To convert from pound-force (lbf) to newton (N)
The real world is not always as simple as what you learned in 5th grade science, when your teacher said "The pound is a unit of weight, not mass", he was correct and incorrect at the same time due to the ambiguous nature of the unit.