Happy Me Thread

[petrw1]

Originally Posted by chalsall

It is kinda cool that I can comfortably fit into 28" waist pants again

Not since I was about 16 years old.
I'm just trying to keep a 36" fitting loose.

[Mark Rose]

Originally Posted by petrw1

Wow 20Kg is about 44 pounds in Canada.

20 kg is only 7.3 pounds on the moon.

[chalsall]

Originally Posted by Mark Rose

20 kg is only 7.3 pounds on the moon.

LOL...

And even on the moon or Mars the men will still hear the enviable question: "Does this space suit make me look fat?

[S485122]

Originally Posted by Mark Rose

20 kg is only 7.3 pounds on the moon.

The kg is a unit of mass and mass does not change with location. 20 kg on earth is still 20 kg on the moon or even in deep space.

Jacob

[kladner]

Originally Posted by S485122

The kg is a unit of mass and mass does not change with location. 20 kg on earth is still 20 kg on the moon or even in deep space.

Jacob

LOL! Excellent reminder!

[Dubslow]

Originally Posted by S485122

The kg is a unit of mass and mass does not change with location. 20 kg on earth is still 20 kg on the moon or even in deep space.

Jacob

The pound on the other hand, as Mark Rose correctly pointed out, is not a unit of mass.

[sdbardwick]

Originally Posted by Dubslow

The pound on the other hand, as Mark Rose correctly pointed out, is not a unit of mass.

The pound is a fine unit of mass.

[science_man_88]

Originally Posted by sdbardwick

Some would disagree.

yeah well I argued about the poundal being force in physics and got told I was wrong so even physic teachers can disagree with that article.

[Mark Rose]

Originally Posted by S485122

The kg is a unit of mass and mass does not change with location. 20 kg on earth is still 20 kg on the moon or even in deep space.

Jacob

Exactly my point. It's the same in Canada as on the Moon. :)

[science_man_88]

Originally Posted by Mark Rose

Exactly my point. It's the same in Canada as on the Moon. :)

really because mass increase is part of special relativity. does it not survive in general relativity ?

[xilman]

Originally Posted by science_man_88

really because mass increase is part of special relativity. does it not survive in general relativity ?

It survives, or not, exactly as it does in special relativity. The reason is that GR reduces to SR in sufficiently small regions of space time where the curvature can be neglected.

The mass increase in SR is entirely a matter of how you look at it. In the inertial frame in which the massive object is at rest its mass is its rest mass, by definition. In other reference frames the mass is greater than the rest mass.

By definition, the kilogram is the rest mass of a lump of metal stored in Paris. This definition may change in the near future but it will still be defined as the rest mass of something.