Cosmo...
If you actually calculated out F=ma you will see that kg is mass and lb is weight. The conversion factor you mentioned (0.45....) is compensated for gravity on the surface of the earth at 9.80665 m/s^2. Anytime something is measured in kg, that is the actual mass of the object. If it's measured in lbs, that is the actual weight of the object on the surface of the earth.
Example:
F = m a, the units being: Newtons = kg m/s^2
F = 1500 kg 9.80665 m/s^2
F = 14,709.975 kg m/s^2
F = 14,709.975 newtons = 3306.93 lbf (pound force)
If you convert 1500 kg to lbs you will see that it equals 3306.93 lbs.
Edit: You will see weight listed as either lbs or kg and you'll see mass as either lbs or kg. It's technically not correct. They're just assuming that you're on the surface of the earth.
Last edited by italia458; 22nd July 2012 at 12:43.