3 ms·

Isn't pound the name of both the mass and force units? In that case it would have the mass 150 pounds, but weigh 25 pounds.

deleted 14y ago
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chris_j 14y ago
When I studied physics in highschool, we were taught to measure mass in kilograms and to measure weight in newtons. While this seemed a little strange at the time, it had the effect of forcing you to be clear which one you were talking about and it avoided this kind of confusion.
- ghaff 14y ago
  As I recall, the mass term "slug" is often used rather than pound-mass to remove this ambiguity. A slug = 32.174049 lbm (i.e. multiplied by the earth's gravitational acceleration constant without any units). But, yes, the terminology among other things can introduce ambiguity and the potential for error when using Imperial units for these types of calculations. (In fact, I seem to remember it sometimes was easier to convert into metric and back again at the end.) The general point here though is that the local gravitational constant changes the weight (downward force on the object) but not its inertia (a property of mass and other physical properties).
mmcnickle 14y ago
It seems you're correct (http://en.wikipedia.org/wiki/Pound_%28force%29 http://en.wikipedia.org/wiki/Pound_%28force%29). It's hugely confusing though. Newtons and Kilograms are much clearer, they're unambiguous even without context.
- stan_rogers 14y ago
  When I was a kid (in Canada) we still did a part of our science/physics education in Imperial units (gravitational FPS), and we used the slug as a mass (inertia) unit, reserving pound for force.
lloeki 14y ago
Now that's one I missed completely. I actually checked fr.wikipedia.org[0] beforehand to be sure, but it made no mention about the force unit, whereas en.wikipedia.org does. [0] http://fr.wikipedia.org/wiki/Pound http://fr.wikipedia.org/wiki/Pound which guides one to http://fr.wikipedia.org/wiki/Livre_(unit%C3%A9_de_masse) http://fr.wikipedia.org/wiki/Livre_(unit%C3%A9_de_masse), this one failing to mention the force unit, except as a secondary connection (http://fr.wikipedia.org/wiki/Livre-force http://fr.wikipedia.org/wiki/Livre-force) down the page.
marvin 14y ago
Aren't they using the term "pounds-force" when explicitly talking about force? I've heard that term used.

deleted 14y ago

[deleted]

chris_j 14y ago

When I studied physics in highschool, we were taught to measure mass in kilograms and to measure weight in newtons. While this seemed a little strange at the time, it had the effect of forcing you to be clear which one you were talking about and it avoided this kind of confusion.

ghaff 14y ago
As I recall, the mass term "slug" is often used rather than pound-mass to remove this ambiguity. A slug = 32.174049 lbm (i.e. multiplied by the earth's gravitational acceleration constant without any units). But, yes, the terminology among other things can introduce ambiguity and the potential for error when using Imperial units for these types of calculations. (In fact, I seem to remember it sometimes was easier to convert into metric and back again at the end.) The general point here though is that the local gravitational constant changes the weight (downward force on the object) but not its inertia (a property of mass and other physical properties).

mmcnickle 14y ago

It seems you're correct (http://en.wikipedia.org/wiki/Pound_%28force%29 http://en.wikipedia.org/wiki/Pound_%28force%29). It's hugely confusing though. Newtons and Kilograms are much clearer, they're unambiguous even without context.

stan_rogers 14y ago
When I was a kid (in Canada) we still did a part of our science/physics education in Imperial units (gravitational FPS), and we used the slug as a mass (inertia) unit, reserving pound for force.

lloeki 14y ago

Now that's one I missed completely. I actually checked fr.wikipedia.org[0] beforehand to be sure, but it made no mention about the force unit, whereas en.wikipedia.org does. [0] http://fr.wikipedia.org/wiki/Pound http://fr.wikipedia.org/wiki/Pound which guides one to http://fr.wikipedia.org/wiki/Livre_(unit%C3%A9_de_masse) http://fr.wikipedia.org/wiki/Livre_(unit%C3%A9_de_masse), this one failing to mention the force unit, except as a secondary connection (http://fr.wikipedia.org/wiki/Livre-force http://fr.wikipedia.org/wiki/Livre-force) down the page.

marvin 14y ago

Aren't they using the term "pounds-force" when explicitly talking about force? I've heard that term used.