English vs. SI units of mass and weight
We know that the SI unit for mass is the kg, and that for force is the newton, where 1 N = 1 Kg x the acceleration due to gravity.
On the other hand, the English unit for mass is the slug, and that for force is the pound, and again we have a similar relationship based on Newton's second law.
My question is, where does the american pound (lb) come from? and where does the conversion 1 kg = 2.2 lb come from?