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I Forge Iron

They redefined the kilogram


Glenn

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1 hour ago, Glenn said:

Metric weights are off so they redefined the kilogram.

Ha ha. At least we have a prototype ... :)

The one thing that intrigues me in that first article is the use of the word "balance" for scale. Rather odd, from the latin, since older scales had to balance a standard weight with the object to be measured. 

So we lost a few micrograms from the prototype ... mm ... i think we are all entitled to a refund.

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Marc,

I had a physics professor who touched on this concept.  A kilogram is a measure of mass, not weight.  Weight is the force of gravity on a mass.  A dual pan mass comparator is commonly called a "balance".  The balance would work equally well in situations with more or less gravity.  A scale, is calibrated to convert the gravitational force of an object into a mass reading.  A load cell in the bathroom scale might give a lighter reading if you were atop K2, than if you were in the Mariannas trench because the force of gravity about earth is proportional to the distance from the center of the earths mass.

 

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Or to put what rockstar.esq said a slightly different way, a scale measures the amount of pressure that a given mass exerts against a spring (or a pressure-sensitive pad,in the case of the fancier electronic ones). If you move that scale from an area with high local gravity (mountaintop) to one with low (deep valley), the force of gravity on that given mass will change, but the springiness of the spring will not. This is actually a good thing, even in a scientific context, because it means that you can use fairly simple equipment to measure variations in the earth's gravity, even if you can't use that same equipment to accurately measure mass.

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Scale and balance are two different things. A balance compares mass under acceleration.

Scale is a graduated method of quantifying difference. I used a tri-scale on the drafting table and a stainless steel architectural scale on the anvil, my tri-square, set is steel a yard stick is a 3' or 36" scale, etc.

The only scale on the thing you weigh yourself on is the dial or electronic readout that tells you you've gained another 2 lbs. 

Of course English is a living language so common usage legitimizes misused words sometimes very quickly.

Frosty The Lucky.

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