How are measurements in kilograms equated to pounds, since kg is a mass and lb is a weight?

Question

I know that wieght = mass * gravity , but I don't think that is what is going on here.

Is it that we are using the pound-mass (lbm), when we say pound?

What is going on, I've always been confused about our system?

I am starting to see the light, thanks.

BUT, why does United States use Pound to describe our weight, and the metric world uses Newtons.

Is it becuase we don't want to say that we weigh 20 slugs?

I meant to say the rest of the world expresses their weight in Kg not Newtons.

Answer 1

> BUT, why does United States use Pound to describe our weight, and the metric world uses [kg, not] Newtons.

That's a good question. Technically, if you're using the metric system "correctly," you SHOULD express your weight in Newtons. I think it comes down to custom rather than correctness.

The first metric unit was the meter, which was supposed to be one ten-millionth of the distance from the equator to the pole. That created the basis for the kilogram, which was supposed to be the mass of 1000 cubic centimeters of water.

From there, the scientists (generally unbeknownst to the public) derived the Newton, as the amount of force required to accelerate 1 kg at a rate of 1 m/sec²

Scientists knew that weight is a force and should therefore be expressed in Newtons. But the general public typically doesn't understand the distinction between mass and weight. But they understood that a kilogram is a thousand cc's of water, and that anything else that weighs the same as a thousand cc's of water, "is" a kilogram. So I think it just became customary to express weight in terms of kg (probably to the frustration of physicists!)

Answer 2

The "conversion" that's commonly employed, 1 kg = 2.2 lb, assumes Earth-normal gravity. What it really means is that a kilogram weighs 2.2 pounds on Earth. (It also weights 9.8 Newtons, in SI units.)

In this regard, kilograms are a more appropriate measure of, e.g., a person's size. My weight, in pounds or Newtons depends on Earth's gravity; my mass, in slugs or kilograms, doesn't.

Answer 3

Slug is English mass unit, pound weight unit. Metric system kilogram mass unit, not know eight unit. On surface earth mass and weight equivalent.

Answer 4

On earth, we generally don't differentiate between mass and weight though you're right they are different entities. I've never heard of a pound-mass as a unit of measure but I suppose we are using it instead of the true weight unit of the pound.

As for the math, 1kg = ~2.2lbs and generally, kg is used for weight outside the U.S. and Mexico (and maybe in mexico as well).

Answer 5

pounds is understood to mean lbm in general usage, except when dealing in engineering applications or in the classroom settings, where they sometimes differentiate between lbm and lb (the force)