What does the customary system measure?

Answer 1

U.S. customary is a system of units that measures the same things that the SI (Systeme International) system of units measure. U.S. Customary is different though, in the way it is derived. The SI system is based on 6 basic concepts, Mass (kg), Time (s), Length (m), Temperature (K), Luminous Intensity(lm), and Electric Current (A). Because mass does not change, SI is considered an absolute system. U.S. customary is based on the pound, which is a unit of force, similar to the Newton in SI units. Because force can change depending on various conditions, U.S. Customary is considered a derived system of measurements. For example, the U.S. Customary unit for mass is the slug. A slug is defined as the amount of mass that can be accelerated at 1ft/s2 by 1 lb. of force. A Newton on the other hand is defined in terms of kilograms, meters, and seconds. This is why if you weigh 150 lb., your mass is only 4.66 slugs or 68.0 kg, and therefore, 667.08 Newtons.