How Do I Convert Pounds to Kilograms?

[Hollywood Dave]

A pound being a measure of weight (force)and a kg being a measure of mass - how would I convert lbs. to Kg? If F=ma, Kg would be on the right of the equation and Lb. on the left which I don't think is equal since a lb. takes into consideration the acceleration of gravity and the Kg does not. I can't seem to put together the acceleration part. If I were to set an equation of - w=mg (w=weight)using the slug as the mass in this equation (similar to the m being the Kg in F=ma)would this be going in the right direction? Pounds v.s Kilograms?

 

[Chi Meson]

YOu are so correct in being bothered about how to convert pounds to kg. When we measure "weight" in kilograms, we are perpetuating a misconception.

What we mean is "the equivalent weight of this number of kilograms on the Earth's surface. Since most people will not go to a place where g is any different, it really doesn't matter on a daily basis.

To convert "kilograms to pounds" you are actually converting "the weight of so many kilograms" to pounds. THe shortcut: take the number of kilograms and multiply by 2.2. This product will be the weight (in pounds) of however many kilograms you have.

 

[russ_watters]

Originally posted by Chi Meson
YOu are so correct in being bothered about this. When we measure "weight" in kilograms, we are perpetuating a misconception.

This is an issue that in practice, both systems screw up. A spring-scale measures weight, and a balance measures mass. In practice, neither differentiates between the two.

 

[Hollywood Dave]

Thanks Chi.
What I am interested in is how do I get to the daily conversion of 2.2 Kg/Lb.? There has to be something or a formula to account for the acceleration of gravity. Can anyone come up with the actual conversion? I have been unable to find anything of the sort.
Hollywood

 

[Chi Meson]

The weight in Newtons: (mass) x (g)

the conversion: one pound of force is exactly 4.448 Newtons.


take your kilograms, multiply by 9.801 m/s^2 (that's "g") then divide by 4.448 Newtons/pound, et voila.

Or, as I mentioned, keep the factor of 9.801/4.448 (that equals 2.203) to go directly from kilograms to pounds. (Remember, if you go to mars, you need to redo this)

 

[Hollywood Dave]

Thanks Chi Menson!
That will help!

To convert from pounds to kilograms, you can use the following formula:

1 pound = 0.45359237 kilograms

To convert from kilograms to pounds, you can use the following formula:

1 kilogram = 2.20462262 pounds

To convert a specific number of pounds to kilograms, you can multiply the number of pounds by 0.45359237. For example, to convert 20 pounds to kilograms:

20 pounds x 0.45359237 = 9.0718474 kilograms

To convert a specific number of kilograms to pounds, you can multiply the number of kilograms by 2.20462262. For example, to convert 10 kilograms to pounds:

10 kilograms x 2.20462262 = 22.046226 pounds

 

[russ_watters]

Originally posted by Hollywood Dave
What I am interested in is how do I get to the daily conversion of 2.2 Kg/Lb.? There has to be something or a formula to account for the acceleration of gravity. Can anyone come up with the actual conversion? I have been unable to find anything of the sort.
Hollywood

That's 2.2 lb/kg. And the formula is f=ma. Make two equations and set a=a. Good luck with the pounds to kg conversion.